# Every Eco owner needs to know this! [ CONFIRMED ]



## usaalways (Mar 29, 2011)

1st I apologize for re posting this topic as it was originally a part of my "ONE thing to change" thread. Just in case no one wanted to change anything and decided to not post there, and I feel every Eco owner needs to know this fact.

GM states in Eco specs that the gas tank is 12.6 gallons, as compared to 15.6 to all other Cruze models, in effort to reduce weight for max fuel economy. I posted that I would want a bigger gas tank, then some faithful posted stated that the gas tanks on ALL Cruze models are the same and that GM engineered for the nozzle to stop at 12 gallons for the Eco. He/she also stated that, with PATIENCE, all we had to do was constantly pump the nozzle for desired fuel capacity. 
Well, this evening it was time to test this as I was at well below for ECU to measure how much fuel I had left.
This photo is my proof that my beloved Cruze Eco was at this pump....






























I begin to fuel. At around 12 gallons my nozzle trips. From 12 on, I stood there for the next 3 gallons constantly flicking my wrist on that dam nozzle...and behold!!!!....15.6 gallons in my Cruze Eco!!! And mind u all, nothing spilled out...








I did wonder why my fuel needle was below the FULL tally, even my salesman insisted that he filled my tank after purchase even though it didin't show. So now Im convinced that my tank is the same as all other models. Next photo shows my fuel gauge ABOVE the fill tally, whereas before letting it fill without the effort was between that next tally.







http://i14.photobucket.com/albums/a320/usaalways


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## VictoryRed08 (Feb 16, 2011)

Hmm, thats interesting. If the gas tank is the same, then why put in the stop? Marketing gimmick claiming reduced weight?


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## usaalways (Mar 29, 2011)

70AARCUDA said:


> ...you must've "coasted" into that gas station if it "took" 15.622 gallons to fill a 15.6 gallon capacity tank!


Hahahah
Actually last I remember on my trip computer was approx. 40 miles left in fuel range. Below that it just stated "low fuel" with no range available.

And if u read my post E-C-O models have a "12.6" ( twelve point six) gas tank capacity..and u can check that at Edmonds, or Chevy's site if u like.

And while I "coasted", I did do a lot, giving such limited time to myself, to make this info available for all ECO owners on this site


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## erlindbl (Apr 12, 2011)

Outstanding..... I am going to have to confirm that at my next fill up. Then I need to figure out what they did and reverse it so I don't have to trickle it in.

Thanks for the info.....


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## GSDB (Apr 5, 2011)

Woo Hoo, I was right! 

So, my theory about the tank size is all based on Max Range for passenger cars. Let's just assume that the government does not want you falling asleep while driving cross country. They can't do anything except limit your range and make you stop for gas. So they came up with a magic number of... 400 miles. So, base on the EPA rating and the magic range number you get tanks size. 

Let's try some math, shall we:

400 miles / 12.6 (stated Eco tank size) = 31.7 MPG, which should be clsoe to the combined fuel rating for the car (28/42)

What do you think of my theory, can anyone find something from the Dept of Trans or Highway Safety people?


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## GSDB (Apr 5, 2011)

usaalways said:


> 1st I apologize for re posting this topic as it was originally a part of my "ONE thing to change" thread. Just in case no one wanted to change anything and decided to not post there, and I feel every Eco owner needs to know this fact.


I almost forgot... Thanks for the post and letting us know. I can't wait to fill'er all the way up.


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## MaximusPrime (Mar 23, 2011)

Heh, in NJ we have full serve, so I'm at the mercy at the gas station attendants.


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## WHITECO (Mar 31, 2011)

Hmm this is interesting....only problem is I think it will mess up my tracking with fuelly??

what you guys think?


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## Vetterin (Mar 27, 2011)

WHITECO said:


> Hmm this is interesting....only problem is I think it will mess up my tracking with fuelly??
> 
> what you guys think?


It shouldn't as you're only giving your mileage and gals used since your last fillup.
On a side note, it is going to be great to get 600 miles on a tank of gas. I'll be filling up on Sunday and will see how much the avg mpg goes down (if any) with the extra gas. It shouldn't be much as you are only adding about 21 lbs to the car.


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## GSDB (Apr 5, 2011)

WHITECO said:


> Hmm this is interesting....only problem is I think it will mess up my tracking with fuelly??
> 
> what you guys think?


Here is my plan. On my next fillup I will let the pump click off and use that number as the gallons for Fuelly. Then I will continue filling all the way to the top. Then the next fill up I will fill to the top again and I will record the total ~15 gallons in Fuelly. Your MPG should look OK, but your miles/fillup will be exagerated this one time.


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## WHITECO (Mar 31, 2011)

Who is a mathmetician and can tell me how many extra Liters of gas that is??

As I am in Canada I don't want to overfill the tank and have it spill on the paint....I can't remember the conversion ratio from US Gallons to Liters


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## chad473 (Feb 21, 2011)

very interesting. my fuel gauge usually shows a hair under full when using the 1 click method as well. I don't know that I would do this very often, but I'll definitely monitor the thread. Could be handy for long trips.


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## WHITECO (Mar 31, 2011)

chad473 said:


> very interesting. my fuel gauge usually shows a hair under full when using the 1 click method as well. I don't know that I would do this very often, but I'll definitely monitor the thread. Could be handy for long trips.


I am thinking great for long trips too!!


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## GSDB (Apr 5, 2011)

WHITECO said:


> Who is a mathmetician and can tell me how many extra Liters of gas that is??
> 
> As I am in Canada I don't want to overfill the tank and have it spill on the paint....I can't remember the conversion ratio from US Gallons to Liters


Online conversion of weights and measures, measurement conversion.

3 gallons = 11.4 Liters


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## Eric123 (Mar 20, 2011)

I'm going to go fairly empty tonight and fill up. Will see how much I can fit into it. I thought the purpose of it was make the tank smaller, which saves weight on fuel and the weight of the tank. However if the tank if the same size and they just let you put in less this means you are just saving weight on 3 gallons or about 15-20 pounds. Seems kind of useless if you ask me. Must have been a marketing thing I guess


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## TGrayEco (Feb 25, 2011)

Hmm...this is interesting. I want to try this, but am worried the gas might spill out.


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## rlhammon (Apr 7, 2011)

I'm not particularly interested in this, or I'd do it... but has anyone called a dealerships parts department to check? If the ECO and other models have the same part number for the tank, it should be clear they are the same.

Using the parts catalog on GMPartsDirect's website they only list one tank, no part number. Isn't conclusive though... they might not have any additional parts shown, and the doesn't mean they don't exist.

I can see why they didn't make a different tank for the ECO... cost. Tooling and then keeping them properly identified so an ECO tank doesn't end up in an LTZ all costs money. I don't know how many ECO models GM forecasted to sell, but I doubt there is a return on the capital investment to make an different gas tank.


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## WHITECO (Mar 31, 2011)

GSDB said:


> Online conversion of weights and measures, measurement conversion.
> 
> 3 gallons = 11.4 Liters


 
Sweet Thank you!!

11 Liters would be about 250 hwy km's on a tank that would be excellent for long trips.


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## GSDB (Apr 5, 2011)

WHITECO said:


> Sweet Thank you!!
> 
> 11 Liters would be about 250 hwy km's on a tank that would be excellent for long trips.


No problem, but you have to hit that gas station soon... we need more data points in Fuelly for the Cruze. There are now 23 showing up on the Cruze page (up from 14 a week ago), but most of our cars are on there yet. It looks like you need to have 3 fillups before they show you (unless you hit, show all).


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## Vetterin (Mar 27, 2011)

70AARCUDA said:


> ...there _might_ be *another* explanation for that *15.622 gallons*-into-a-*12.6 gallon* Eco tank!


 I'm listening...........


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## TSURacing (Jan 1, 2011)

WHITECO said:


> Who is a mathmetician and can tell me how many extra Liters of gas that is??
> 
> As I am in Canada I don't want to overfill the tank and have it spill on the paint....I can't remember the conversion ratio from US Gallons to Liters


I thought every male in North America knew that conversion.

1gal/3.8L per flush. Its stamped into the top of most every urinal.


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## WHITECO (Mar 31, 2011)

GSDB said:


> No problem, but you have to hit that gas station soon... we need more data points in Fuelly for the Cruze. There are now 23 showing up on the Cruze page (up from 14 a week ago), but most of our cars are on there yet. It looks like you need to have 3 fillups before they show you (unless you hit, show all).


Should have another fillup in about a week...I can't help that it takes forever to go through a tank


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## Seth (Feb 19, 2011)

Good to know!


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## ChevyCruzeLTZ (Apr 7, 2011)

I wonder if you get the same results at another gas station, just because it says 15 gallons on the pump doesn't mean 15 gallons came out.


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## ChevyCruzeLTZ (Apr 7, 2011)

I suppose you could fill three 5 gallon gas cans and see if you can get them all in there.


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## our1vue (Apr 12, 2011)

I think the best check would be to see if the tanks (eco vs normal) have the same part number. Maybe the tanks are the same, but they have a different filler tube that has a brick on the end to displace 3 gallons of gas. Or maybe they put a brick in the tank to displace 3 gallons of gas. A parts list would reveal the secret. Are the parts list out yet or do you have to wait for the service manuals next month ?
I think the designers at GM went a little overboard with the weight savings. Well maybe not overboard, but not as smart as they could have been (no spare, less gas,
less sound insulation, etc). They seem to be effecting the usability features of the car. (Heck, lets just take out the rear seat, most of the time, only 1 or 2 people are in the car  I wonder how much their 42 mpg would drop if they kept the aerodynamic and gearing changes, but dropped all their weight saving changes.


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## WHITECO (Mar 31, 2011)

our1vue said:


> I think the best check would be to see if the tanks (eco vs normal) have the same part number. Maybe the tanks are the same, but they have a different filler tube that has a brick on the end to displace 3 gallons of gas. Or maybe they put a brick in the tank to displace 3 gallons of gas. A parts list would reveal the secret. Are the parts list out yet or do you have to wait for the service manuals next month ?
> I think the designers at GM went a little overboard with the weight savings. Well maybe not overboard, but not as smart as they could have been (no spare, less gas,
> less sound insulation, etc). They seem to be effecting the usability features of the car. (Heck, lets just take out the rear seat, most of the time, only 1 or 2 people are in the car  I wonder how much their 42 mpg would drop if they kept the aerodynamic and gearing changes, but dropped all their weight saving changes.


I think probably enough to no longer make the car the mpg leader in it's class. Remember they only need 1 model to be able to advertise the claims. It's my understanding that they only planned to sell 10% of the total cruze sales as the Manual Eco version of the car.


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## existensil (Apr 13, 2011)

Siphoning of bubbling vapors could explain some difference between what the pump shows and how much gas you actually put in your car, but 3 gallons worth is pretty preposterous.

Even pumping very slowly, the gas would have started spilling out if the tank was really 12.6 gallons.

My Subaru is almost 100% full at the first click, and every attempt I've made at slowly pumping more in (pumped as slow as humanly possible at more than one gas station) has resulted in me spilling gas. That would explain why the manual says never pump past the first click on that car 

If the Cruze's nozzle is specifically designed to stop at ~12.6 gallons and you were able to squeeze another 3 in there, then I can think of only two possible explanations:


The tank really is 15.6 gallons and is being artificially limited to 12.6
Those extra 3 gallons were flowing SOMEWHERE, possibly beneath your car. Did you smell gas? Did you see a river of gas flowing to the drain at the pump?

I am skeptical that the gas pump measurement was off by 3 gallons or that the pump was able to siphon back that much. Gas pumps are heavily regulated and regularly inspected and certified. The pumps measure pretty accurately. I've read of gas stations getting into trouble because ground water seeped into their tanks, so they were selling half-water-half-gas to their customers... but the volume on the pumps was still accurate. Sounds like you definitely pumped 15.6 gallons of SOMETHING, SOMEWHERE.

At this point the most logical explanation seems to be that the size of the tank is artificially limited. A smaller tank is another extra part, adding cost and complexity, and nets you only a negligible weight saving compared to just making the tank accept less fuel.

I would really like to see some more investigation into this, both as to whether the part numbers are the same, and whether these extra 3 gallons are being used and resulting in significantly increased range.


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## existensil (Apr 13, 2011)

I'm sure your right about the pump gulping back fuel when it "clicks", but I don't think the metering regulations would allow them to get away with siphoning at a rate that equals the flow rate when pumping very slowly. I am just skeptical that this is possible, but if you have some proof of this phenomena I would be willing to take a look.


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## gfxdave99 (Feb 26, 2011)

I filled up last night i will have to try it now


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## ChevyCruzeLTZ (Apr 7, 2011)

Another thing to consider, the reason the owners manuals tell you not to keep pumping after the pump shuts off is that the vehicles evaporative emissions system can get filled with fuel this way and cause the engine to run rich. A fuel soaked charcoal canister would have to be replaced.


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## existensil (Apr 13, 2011)

70AARCUDA: I was about to buy your explanation for the missing 3 gallons based on your relevant anecdote and your allusion to additional research you have done. However, I am a curious fellow and decided to do some reading of my own.

I'm now back to not being convinced one way or the other.

I would like to point out a couple small things, though. It does not appear the EPA has anything to do with regulating fuel pumps. My research indicates that the Weights and Measures Division (WMD) of the National Institute of Standards and Technologies (NIST), part of the US Commerce Department, is who regulates fuel pumps and their accuracy.

It appears that fuel pumps must be within a tolerance of 0.03% and I could not find anything which would allow this tolerance to increase when the fuel is pumped extremely slow.

I also read a bit about how modern fuel pumps work (albeit only what I could read in 10 minutes), and it seems the fuel is measured at the pump (base of the hose) while the shut-off valve is a part of the handle assembly. There does not appear to be any mechanism for a significant volume of fuel to flow the other way. In fact, the design of the pump suggests that once the fuel is pumped into the hose it will either stay there or go out, as the pump is strictly one way and creates a seal that will never allow gas to flow backwards.

I am still on the fence about this who discussion since there might be some additional mechanism in the pumps I have not been able to find a description of in my reading, and I haven't seen further evidence about whether the Cruze Eco tank is the same part as used in the other Cruze trims. I would also like to see the results of some range test from those who have "fit" 15+ gallons in their Cruze.


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## Seth (Feb 19, 2011)

This can be solved pretty easily by using a gas canister.


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## existensil (Apr 13, 2011)

70AARCUDA said:


> ...read about the EPA pump fuel/vapor "recovery" requirements.
> 
> ...it's especially "invisible" in CARB land because the huge accordian collars hide both sound and smell from you...and all feel of fuel being siphoned back to the tank.


I found some literature on this and am reading some of it now. Thank you very much for patiently putting up with my skepticism and I appreciate you remaining open minded about the possibility of alternate explanations.


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## jlalill (Nov 1, 2010)

WHITECO said:


> Who is a mathmetician and can tell me how many extra Liters of gas that is??
> 
> As I am in Canada I don't want to overfill the tank and have it spill on the paint....I can't remember the conversion ratio from US Gallons to Liters


use this conversion link

Unit Conversions


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## existensil (Apr 13, 2011)

I'm still not 100% convinced that 3 whole gallons can be explained away by the vapor recovery systems in modern pumps. However, this helpful guide from the EPA has led me to believe that at least *some* of the gas is going back to the pump when you keep pumping beyond the "click." So, you are loosing at least a little money right there.

Don't Top Off Your Gas Tank! | Mid-Atlantic Air Protection

This guide also gives other good reasons NOT to top off, including the fact that the release of additional vapor is unhealthy to the person pumping and contributes to poor air quality and o-zone depletion. I'm also sure many of us are aware of the effects evaporating gasoline can have on paint if you spill some and don't completely wipe it up.

If the Cruze Eco really has a 15.6 gallon tank and is being artificially limited by it's nozzle it sounds like I'm going to put 12.6 into mine until someone comes out with an easy-to-follow guide on modifying the tank nozzle.

Still a very interesting discussion and I hope we get to the bottom of this.


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## existensil (Apr 13, 2011)

I found something else out that is relevant to this discussion:

Cars manufactured in 1998 or later are required to have their own vapor recovery systems. So the car's vapor recovery system works in concert with the pump's own vapor recovery system to dramatically reduce the gas vapor released when pumping gas.

If the Cruze Eco has the 15.6 gallon tank it may be fighting with the fuel pump for capture of the vapors and 'usaalways' may very well have gotten nearly 15.6 gallons into his tank (though it seems like the actual number is likely to be lower).


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## Eric123 (Mar 20, 2011)

This is Confirmed!!

So today I drove my Cruze Eco nearly empty. I drove it until the low fuel light came on. At which point I continued until my display would not longer provide me the km until empty. It just said "fill up". I went to the gas station and filled up. The nozzle clicked off at 42 litres (11.02 gallons). I continued to fill at a very slow speed (took 10 minutes). When filling it would start to come up the top of the nozzle and then it would drain it. I kept doing this and then it changed. When it was finally really full it would drain very differently and spill over. The fill tube was now full. Normally I would never do this but I wanted to confirm this. When I looked at the pump I had put in 59 litres (15.59 gallons). Mind you a little gas spilt because I was trying to speed it up. It is painfully slow to do however it is confirmed. Our gas tank is the same size but the nozzle clicks off sooner. Also to note in Canada our pumps do not have the same nozzle as in the US. Our's does not have the fuel and vapour recovery. We get to spill and enjoy all those fumes 

I'm a little disappointed that it is true. It is not something I will do again as I stood at the pump for over 10 minutes but it took it all! I wish there was a way to remove it!


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## existensil (Apr 13, 2011)

Great news! Thanks, eric123!

Now I just hope someone with more knowledge and guts than me will figure out how to modify our nozzles to recover the missing 3 gallons of capacity


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## ChevyCruzeLTZ (Apr 7, 2011)

I'm not an engineer, but if I wanted to make a fuel pump shut off before the tank was full I would lower the vent into the tank, when the air can no longer escape through the vent the fuel will come up the filler neck and shut the pump off. So if this is true I would think that it might be possible to modify the vent so that the tank can be filled.


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## gman19 (Apr 5, 2011)

Certainly a possibility...


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## Eric123 (Mar 20, 2011)

So I've put 250 km since I filled the ECO tank completely full. I still haven't hit the full mark on the fuel gauge. I'm still sitting above it


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## usaalways (Mar 29, 2011)

eric123 said:


> This is Confirmed!!
> 
> So today I drove my Cruze Eco nearly empty. I drove it until the low fuel light came on. At which point I continued until my display would not longer provide me the km until empty. It just said "fill up". I went to the gas station and filled up. The nozzle clicked off at 42 litres (11.02 gallons). I continued to fill at a very slow speed (took 10 minutes). When filling it would start to come up the top of the nozzle and then it would drain it. I kept doing this and then it changed. When it was finally really full it would drain very differently and spill over. The fill tube was now full. Normally I would never do this but I wanted to confirm this. When I looked at the pump I had put in 59 litres (15.59 gallons). Mind you a little gas spilt because I was trying to speed it up. It is painfully slow to do however it is confirmed. Our gas tank is the same size but the nozzle clicks off sooner. Also to note in Canada our pumps do not have the same nozzle as in the US. Our's does not have the fuel and vapour recovery. We get to spill and enjoy all those fumes
> 
> I'm a little disappointed that it is true. It is not something I will do again as I stood at the pump for over 10 minutes but it took it all! I wish there was a way to remove it!


Im glad someone helped prove the tank is, in FACT, bigger then 12.6 gallons
Now IM open to ideas on exactly how much bigger, or how much i actually got in the tank, but Im sure it is bigger then 12.6 gallons. Why? No, not stubborn at all, but EVERY ECO owner can conclude that if let the nozzle trip by itself, the fuel NEEDLE IS BELOW THE FILL TALLY, and my photo of my fuel gauge shows the needle ABOVE THE FILL TALLY
In addition I put a little over 50 miles since the fill up and needle is still above fill tally


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## WHITECO (Mar 31, 2011)

eric123 said:


> So I've put 250 km since I filled the ECO tank completely full. I still haven't hit the full mark on the fuel gauge. I'm still sitting above it


This is what I thought would happen...an extra 250km's per tank....This will be great for long trips...800km's on a tank...Nicely done


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## eriecruizer (Mar 6, 2011)

*1gal/3.8L per flush*

Re TSURacing's conversion factor: Not wanting to be a sharpshooter, but over the long haul, small differences grow .... maybe folks should use 3.7854 litres per US gallon. Just a thought. I would be more concerned about temperatures affecting volume pumped than this small (0.0146) difference, but, again, differences add up.


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## WHITECO (Mar 31, 2011)

eriecruizer said:


> Re TSURacing's conversion factor: Not wanting to be a sharpshooter, but over the long haul, small differences grow .... maybe folks should use 3.7854 litres per US gallon. Just a thought.


 
If I was going to overfill, I would just put 10 liters in so I would have to worry about overfilling and spilling


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## Silphion (Mar 31, 2011)

I would like to point out the ECO A/T does not have the 12 gal limitation. The DIC and my wallet both provide proof of a 15.6 gal tank, as I last pumped in 14 gal before it 'clicked' on me.


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## Vetterin (Mar 27, 2011)

To eric123 and anyone else that has put in more than 12.6 gals what did your DIC show as to mileage remaining or gals remaining? I am wondering if the DIC is also "tripped" to max out based on the 12.6 gal figure.
I'll be filling up this weekend but am only filling till the first shutoff. Then I'm driving home and adding 2 gals from one of my fuel cans at "full dump speed"  and see what happens and let you know.


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## TGrayEco (Feb 25, 2011)

Silphion said:


> I would like to point out the ECO A/T does not have the 12 gal limitation. The DIC and my wallet both provide proof of a 15.6 gal tank, as I last pumped in 14 gal before it 'clicked' on me.


That's odd because mine always "clicks" off around 12 gallons....maybe I'll try to fill up more next time I fill up...


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## Silphion (Mar 31, 2011)

Truelly? Whenever I fill to full, I usually have '15 gal remaining' displayed on both the DIC and OnStar app. Last time around, I let the fuel dip below 1/4 tank, and filled up before the low-fuel light came up. As the receipt proved, I pumped in ~14 gallons tha day.


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## TGrayEco (Feb 25, 2011)

Silphion said:


> Truelly? Whenever I fill to full, I usually have '15 gal remaining' displayed on both the DIC and OnStar app. Last time around, I let the fuel dip below 1/4 tank, and filled up before the low-fuel light came up. As the receipt proved, I pumped in ~14 gallons tha day.


Hmm...that's weird. I guess next time I fill up I'll pay a little more attention, see if I can't get more gas in the tank.


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## Eric123 (Mar 20, 2011)

Vetterin said:


> To eric123 and anyone else that has put in more than 12.6 gals what did your DIC show as to mileage remaining or gals remaining? I am wondering if the DIC is also "tripped" to max out based on the 12.6 gal figure.
> I'll be filling up this weekend but am only filling till the first shutoff. Then I'm driving home and adding 2 gals from one of my fuel cans at "full dump speed"  and see what happens and let you know.


My gas got so low my DIC no longer displayed km's to empty. It just told me to fill up. It is possible to add more gas....but is painfully slow. Starting to sound as though it may be only the 6 speed manual that has this limitation...


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## jan (Apr 16, 2011)

jlalill said:


> use this conversion link
> 
> Unit Conversions



Wauw, that's a terrible site. I recommend ConvertKing.net. It's the leading site for accurate conversions.

Jan


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## GSDB (Apr 5, 2011)

jan said:


> Wauw, that's a terrible site. I recommend ConvertKing.net. It's the leading site for accurate conversions.
> 
> Jan


 
I still like mine the bestest, Online conversion of weights and measures, measurement conversion.. It will show the conversion factors for all units on one page. Try it on the distance/length page


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## Drew1985 (Mar 13, 2011)

Model Information - Online Ordering Guide it does show that the Eco AT has a 15.6 gallon tank the MT has a 12.6 tank


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## usaalways (Mar 29, 2011)

Drew1985 said:


> Model Information - Online Ordering Guide it does show that the eco at has a 15 gallon tank the mt hasa 12 tank


"Specs" will always show that the Eco will have a 12.6 gallon tank for as 
long as GM wants to. This is in no violation of any laws. For something like, lets say for example, emmissions claimed are a lot less then actual output(somehow gets by EPA), then that would NOT be allowed.
As one previous poster says in his/her theory, it may be something to do with the Dept of Trans._ wanting, _not _requiring_, 400 miles from a tank in order to rest by stopping for fuel and not falling asleep at wheel. And thus the tank is engineered to trip the nozzle at 12.6 rather then 15.6, making 400 miles. In addition another poster stated no financial gains making a different tank for only 1 model, which makes a lot of sense.
Anyway this photo was taken last night. I filled and trickled nozzle as per original thread photos last Wed night. Trip 1 miles show 168.5, and I reset Thur morning after 11.7, so at 180 miles so far(approx 60 miles all highway, 120 city) needle is yet to fall below fill tally.
Nothing against GM or anyone, but the tank is the same as all other Cruze models


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## usaalways (Mar 29, 2011)

*whoa...look at that needle fall!*

So, the next 110 miles today have burned the gas that is supposed to be in the tank. Today did do some "stop and go" for some more miles then usual, and pure highway, with cruise set at 61 was only about 40 of total(a lot of wind today in eastern PA).
1st photo is "291.4" total trip with current tank(mind you it was reset next day after putting 11.7 following fill**), and 2nd is approx fuel range left at 304.
Math adds up to getting my desired 600 miles from a tank. But we will see.
Will be difficult to prove this since below 40 miles for fuel range, i believe it's 40 from last time, turns to "Low fuel range".

** Just in case there are some who want to know why I reset...because I wanted to get my precise distance/from work)


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## Mrk9182 (Apr 8, 2011)

Just letting you guys know that the ecos have 2 seperate fuel pumps listed in the eco parts catalog, one is listed as 1.4l w/13 gal tank the other is 1.4l w/o 13 gal tank. I would not recommend over filling your cars


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## usaalways (Mar 29, 2011)

Mrk9182 said:


> Just letting you guys know that the ecos have 2 seperate fuel pumps listed in the eco parts catalog, one is listed as 1.4l w/13 gal tank the other is 1.4l w/o 13 gal tank. I would not recommend over filling your cars


This is such great info. Thanx for posting.
Why would over filling be a negative?


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## Mrk9182 (Apr 8, 2011)

if you over fill the car there is a possibility that fuel will fill up the charcoal canister, which is for filtering fuel vapors out when you filling the vehicle. This can ruin the canister and any of the valves in the evaporative emissions system.


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## usaalways (Mar 29, 2011)

Mrk9182 said:


> if you over fill the car there is a possibility that fuel will fill up the charcoal canister, which is for filtering fuel vapors out when you filling the vehicle. This can ruin the canister and any of the valves in the evaporative emissions system.


This is something to think about before I attempt to do this again. I was thinking to bring along my portable tank I use for my power tools to fill the extra 3 gallons when I get home from the pump, but now that's on hold.
Thank you for the warning!


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## SilverCruzer (Nov 30, 2010)

TSURacing said:


> I thought every male in North America knew that conversion.
> 
> 1gal/3.8L per flush. Its stamped into the top of most every urinal.


Exactly! I too know this conversion for this reason, especially since I used to own a Ford LTD with a 3.8 L engine.


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## GM_6T40_Trans_Engineer (Feb 26, 2011)

OMG, conspiracy theories!! I have yet to find a vehicle you can't overfill. I've driven a car with a 12gal tank for a LONG time that I could routinely put 15+ gallons in it. 

For the record, the ECO/Non-Eco models have the same tanks and filler necks. 

My guess is the difference is the "cal" for the fuel pump assm (level sender), which would mean the ECO has a larger reserve because it hits "empty" sooner. 

*Disclaimer: I'm not the release engineer for the fuel tank. *


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## WHITECO (Mar 31, 2011)

I am really interested in the results of this...man an extra 250km's to a tank when I am on a long trip is huge!!


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## GSDB (Apr 5, 2011)

GM_6T40_Trans_Engineer said:


> OMG, conspiracy theories!! I have yet to find a vehicle you can't overfill. I've driven a car with a 12gal tank for a LONG time that I could routinely put 15+ gallons in it.
> 
> For the record, the ECO/Non-Eco models have the same tanks and filler necks.
> 
> ...


Why exactly is this conversation "conspiracy theory"? If every model of the Cruze has the exact same tank, but only the Cruze Eco MT is listed in the literature as having a smaller tank, is it unreasonable to ask, why?

Is your last statement saying that all the Cruzes carry the same amount of gas, but the ECO MT low fuel light comes on 3 gallons sooner than the others?


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## Eric123 (Mar 20, 2011)

The issue I found with trying to fill the tank is it does not fill fast enough. Even if I changed from the gas pump to a portable can it wouldn't make a difference. There is something in this tank that when it reached a certain level it constricts the filler neck and causes the pump to shut off. It also causes it to drain into the tank VERY slowly. I could watch it drain out of the filler neck thats how slow it was. I wish I knew how it worked...and how to stop it


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## Eric123 (Mar 20, 2011)

In Canada we do not have the same style of pump. They do not have this feature. The pump clicks off when it reaches the "47 litre" full mark that the ECO tank seems to have. However I can continue to fill but it drains very slowly in. GM has made this tank seem smaller then it is by constricting the flow into the tank once it reaches the 47 litres and causing the neck to back up and trip off the pump when in fact the fuel in the neck will slowly drain into the tank and you can continue filling. This is why it took me nearly 10 minutes to put in the last 11 litres. If I had a portable can I would have had to just poor it really slowly. I understand how GM did it... I guess what confuses me and everyone else is why. Makes me think the part about restricting how far you can drive between fill ups that a previous poster mentioned may be true.


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## Eric123 (Mar 20, 2011)

That's the one!


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## Blue Angel (Feb 18, 2011)

GM_6T40_Trans_Engineer said:


> For the record, the ECO/Non-Eco models have the same tanks and filler necks.
> 
> My guess is the difference is the "cal" for the fuel pump assm (level sender), which would mean the ECO has a larger reserve because it hits "empty" sooner.
> 
> *Disclaimer: I'm not the release engineer for the fuel tank. *


Disclaimer? That sounds a little flaky...

"The sky is green." *Disclaimer - I'm color blind* 

I think you would have to agree there is something different between the cars. What's going on here is the search for that difference. If the Eco had a larger (i.e. 3 gallon larger) "reserve" then there would be no weight savings... just 3 gallons of fuel capacity that never got used.



ChevyCruzeLTZ said:


> I'm not an engineer, but if I wanted to make a fuel pump shut off before the tank was full I would lower the vent into the tank, when the air can no longer escape through the vent the fuel will come up the filler neck and shut the pump off. So if this is true I would think that it might be possible to modify the vent so that the tank can be filled.


This makes the most sense of any theory thrown out there so far. If indeed the Eco MT tank is the same part number as the other cars then maybe there are two locations on the tank to hook up the filler neck vent?

Having the same part number with an "option" of how it is installed goes against my experiences in assembly plants... everything is "error proofed" as much as possible. Inevitably there would be AT cars getting 12 gal. "capacity" and MT cars getting 15 gal. "capacity". I guess we'll need to see an actual part number verification to prove/disprove this.



Mrk9182 said:


> the ecos have 2 seperate fuel pumps listed in the eco parts catalog, one is listed as 1.4l w/13 gal tank the other is 1.4l w/o 13 gal tank. I would not recommend over filling your cars


Usually the fuel pump and sender unit is all one assembly, so the ECO MT likely has a sender that's calibrated to show "full" at a lower fuel level in the tank. I don't think this would have anything to do with overfilling being hazardous, but it is interesting since Eco MT owners are seeing that even after filling their tanks (12.6 gallons worth, or the usual one click) the fuel gauge displays just slightly less than "full". Hmmm...

Does anyone here who works for a GM dealership care to spend a few minutes looking into this? If they were to not want to identify themselves they could PM me the info and I would post it here to keep their identity hidden...

I'm curious to know what's going on with the tank! If it's a simple part swap (i.e. new vent hose or similar) I bet a lot of people on this board would be interested in performing such a modification. Just for kicks, 42MPG x 15.6 Gal. = 655 miles/tank, or 1054 km/tank! Pretty sweet for long trips if necessary! 

FYI, on a highway trip the extra weight of the fuel would make no measurable difference (practically speaking, of course) to your mileage. Reducing weight plays a big part in reducing city driving consumption as there is less weight being accelerated all the time. Once the weight of the car is up to speed any extra weight would only cause a proportional increase in rolling resistance from the tires.


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## Eric123 (Mar 20, 2011)

Blue Angel said:


> Disclaimer? That sounds a little flaky...
> 
> "The sky is green." *Disclaimer - I'm color blind*
> 
> ...


Not to mention that amount of fuel doesn't even weigh that much. About the difference between a male or female driver. So I doubt GM did it for weight savings


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## SilverCruzer (Nov 30, 2010)

Eric123 said:


> Not to mention that amount of fuel doesn't even weigh that much. About the difference between a male or female driver. So I doubt GM did it for weight savings


Well...I kind of think they did because this and the other times all add up.

A tire pump instead of a spare
no power seat adjustment
slightly lighter wheels
less sound insulation (this one I am not sure about)
Each of these is not much, but its the sum of the parts (or lack there of) that makes the difference.


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## Blue Angel (Feb 18, 2011)

^ Yep.

My '02 Z06 is the same way; a pound here, a couple pounds there... the fixed roof/short rear window body style, thinner F/R glass, lighter battery (5lbs), lighter wheels and tires, titanium exhaust, fixed non-power antenna, delete power seat on pass. side, all of these things add up to a significant weight savings while on their own would hardly be worth mentioning.

Oh, and I never go to the drag strip with a full tank of fuel in that car - filling it up adds about 100lbs of fuel - that's over a 3% increase in race weight!

The lighter fuel load was a very easy way for GM to shed some weight from the Eco, and with its extra frugality on the highway, wasn't really compromising on overall driving range by much.


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## Mrk9182 (Apr 8, 2011)

I highly doubt gm has a conspiracy to only let you fill the tank with 12 gal when it is a 15 gal tank. They have no advantage to lie about the size of the tank. 

I will go on with my 12 gal tank and i am fine with that 

P.S. who needs really wants to drive 8 plus hours straight. A gas stop is a great excuse to stretch your legs.


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## zz_cro (Apr 22, 2011)

If your theory is correct...then why VW jetta diesel can go a lot further than 400 miles on a tank. I think GM tried to limit weight of the vehicle without the expense of separate tooling and extra part on the assembly line. That's my guess anyway.


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## zz_cro (Apr 22, 2011)

I have red somewhere before that every 100lbs of weight is worth 1% of fuel consumption. A little bit here, a little bit there and it adds up.


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## erlindbl (Apr 12, 2011)

Everything that I have heard is that they used the eco manual to get the best gas mileage to sell the car. The car sold has to be the exact same as the one tested. If they went to the extent of not even allowing us to order a spare tire with the car, why is it so hard to believe they modified the tank to save the fuel weight. You can get the spare with the auto eco but not the manual. Also why spend the money to make a different tank. They simply modified it so it holds less gas to save the weight and get their magic 42 mpg #. You don't see them advertising the eco autos mileage. Seems the most logical explanation to me.....


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## Seth (Feb 19, 2011)

We need to figure out how to fix this without having to sit at the pump for 10+ extra minutes. Reverse engineer?


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## existensil (Apr 13, 2011)

This is one part of the car I am a bit frightened to mess with... hoping someone with more knowledge/guts will put together a nice guide.


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## MaximusPrime (Mar 23, 2011)

Here in NJ, we have full serve, and I've noticed my Eco pumps about 13.5-14 gallons into the tank before it registers full. This was a line or two below E as well, so I wasn't running on fumes (computer said I have over 70 miles range left)


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## Vetterin (Mar 27, 2011)

Well yesterday I had no problem putting another 1-1/2 gals in my tank after the pump clicked off. I just pulled the nozzle half way out and added on slow speed with no problem. I could have put in more but didn't feel a need to. I don't think it even took 1 minute. Anyway, today after 42 miles my gage is still over the full mark.


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## Chefmaster87 (Mar 30, 2011)

I didn't know this.. I was thinking something like that but it makes sense chevy would do that. Next time I get gas I'll have to try that!! 
Thanks for the heads up!!


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## TGrayEco (Feb 25, 2011)

I did this last time I filled up....won't do it again as it did take a little longer having to go very slowly towards to end of filling up.


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## gfxdave99 (Feb 26, 2011)

So I'm not convinced. Maybe i havent let my tank go low enough. I had my car "full", and drove until it was at 10.0 gallons used according to the trip computer and i managed to pump about 10.5 before even with the gentlest pumping i started to spill over.

I also wonder if maybe some cars depending on the build have a different tank


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## Nightdrv (Apr 17, 2011)

We need part #'s on the entire fuel assembly of both the MT and AT Eco's. End of story.


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## ChevyCruzeLTZ (Apr 7, 2011)

If I was to guess and if they did what I think they might have, I would bet there is a separate part number for the eco tank with the lowered vent and not an option as to how to install it. It would be a simple and cheap modification to the existing tank without needing new molds or anything like that.



Blue Angel said:


> Disclaimer? That sounds a little flaky...
> 
> "The sky is green." *Disclaimer - I'm color blind*
> 
> ...


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## usaalways (Mar 29, 2011)

Nightdrv said:


> We need part #'s on the entire fuel assembly of both the MT and AT Eco's. End of story.


Part #'s and all would obviously cure the proof needed on whether the tank is different or not. Well I have shown,and so has another, in my photos that I got the 3 gallons past the advertised "12.6" tank specs _suggests. _
My point was not to point to any kind of conspiracy by GM or anything of the sort, just to prove that the fuel tank _capacity_ is the same on all Cruzes'. It's possible the tank is a different part#(i guess), but the actual capacity is certainly more then 12.6 US gallons.
And Im not saying that GM should not have done this(and of course not saying we all should do this). It all comes down to simple process of elimination used in the business world. In a nutshell when companies need to cut, they simply slash entities on paper and execute. In this case, engineers were paid to cut weight and fuel weight was one on the list.
Following photos show the results from the experiment. Approx 280 miles pure interstate no greater then 65 MPH. Difference is mix of "suburban"(not too many lights) and only about 10 miles of gung-ho stop and go.
My next endeavor is to conclude whether it is harmful to my Cruze in anyway.
1) Final miles from fill up. And again add 11.7 miles as I reset it next morning after. 2) Gallons used(more then 12.6, correct?) 3) Shows ave trip miles, and with filling at 15.6 from original compared to #2 photo, I could have gotten more miles driven 4) Just had to fill again . All in all 600 miles is possible from 1 full tank in the ECO!


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## Blue Angel (Feb 18, 2011)

existensil said:


> I found something else out that is relevant to this discussion:
> 
> Cars manufactured in 1998 or later are required to have their own vapor recovery systems. So the car's vapor recovery system works in concert with the pump's own vapor recovery system to dramatically reduce the gas vapor released when pumping gas.
> 
> If the Cruze Eco has the 15.6 gallon tank it may be fighting with the fuel pump for capture of the vapors and 'usaalways' may very well have gotten nearly 15.6 gallons into his tank (though it seems like the actual number is likely to be lower).


Something to add to this discussion…

I went for a road trip to New Hampshire (from Ottawa) on the weekend. On the way back up through Vermont we stopped to get fuel at the Mobil1 station on Derby Rd. between I91 and Newport. That Mobil1 station had the "Vapor Recovery Nozzles" on their pumps.

The nozzle had a small "bellows" that compressed against the filler opening while pumping gas. This appeared to be a way of sealing to limit vapor release. In my opinion, there's no way the seal formed between this bellows and the filler opening would be robust enough to "vacuum" liquid fuel without major spillage. Actually, since the bellows is constructed of a relatively flimsy soft plastic/rubber material of little strength I would bet the amount of vacuum required to suck liquid fuel upwards from the filler neck would collapse that bellows.

Another thing to think about is if the bellows had liquid fuel running through it there would be lots of fuel "sitting" in the bellows when you pulled the nozzle out of the filler neck, and this would drip and run all over the place.

If I had to guess, there is a small vacuum line connected inside this bellows that applies a very slight vacuum to the filler neck while fueling to suck up any fuel vapors that are pushed out of the tank as they are displaced by the fuel going in (an equal volume of dense fuel vapor will be pushed out of the tank for every bit of fuel that's pumped in).

Since the car's engine is "off" while re-fueling takes place, there would be no amount of useful "vacuum" available in the car's vapor management system to contribute to this vapor recovery process leaving the task soley to the pump (while re-fueling).

That's my semi-educated guess/hypothesis on the topic. I'm going to stick with my earlier guess that the poster who suggested the tank vent location being the culprit is correct. I'm also going to guess that if the pump says you got 15 gallons into your "12 gallon" tank, you got 15 gallons into your 12 galon tank.


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## abyh20 (Feb 27, 2011)

I was so happy to find this. After filling my m6 eco up at the quarter-tank mark I was surprised to see that she took 13.4 gallons. I thought either the pump ripped me off or I spilled fuel somewhere. This is an awesome find.


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## GM_6T40_Trans_Engineer (Feb 26, 2011)

Tank is the same. 



A better guess as to why the difference would be the calibration of the fuel level sender/ECM/BCM.* (*Disclaimer: I'm not a fuel system engineer.)

Looks like someone was on to that...



Blue Angel said:


> Usually the fuel pump and sender unit is all one assembly, so the ECO MT likely has a sender that's calibrated to show "full" at a lower fuel level in the tank. I don't think this would have anything to do with overfilling being hazardous, but it is interesting since Eco MT owners are seeing that even after filling their tanks (12.6 gallons worth, or the usual one click) the fuel gauge displays just slightly less than "full".


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## davhamm (May 2, 2011)

*Some facts*

Hi all, I might be able to add some facts.

When you put gas into the tank the air that is replaced with gas has to go somewhere. Now it could go through a hole at the top of the tank, but then so could gas a fumes. So.... how about a hole that is piped to the famous vapor recovery canister. If there was some way to close that hole when the tank got full.. Hmmm maybe a float that has something on top to close up the hole. Once the hole is closed the pressure in the filler neck goes up and the gas pump sense this and shuts off. If you slowly add gas, the pressure doesn't go up enough and the pump lets you keep going. Of course since the float has blocked the hole, the gas cant get to the vapor recovery system. 

SO if you wanted to have the car weigh less for Fuel economy testing but did not want a new tank you could just change that float or add a small spacer... Of course that float has to be on something, and since its hole attaches to a hose just like the fuel pump, maybe you could put it on that module? 

Oh and yes the Auto Eco gets the bigger tank:

GM News - United States - Cruze and Cruze Eco

EPA-est. fuel economy (city / hwy):
1.8L DOHC I-4
26 / 36 (manual) 
22 / 35 (automatic)
1.4L turbocharged DOHC I-4
24 / 36 (LT, LTZ) 
28 / 42 (Eco manual) 
26 / 37 (Eco automatic)

Oh and since my company requires me to add this. I work for GM and none of what I have stated is a comment from GM but my own personal thoughts. *note not a fuel systems guy (N&V) but I do know some*


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## Seth (Feb 19, 2011)

Thanks for the input Dav, I am really hoping to find a real solution for this because its a pain to slowly drip the gas and it is also annoying that the fuel gauge isn't ever full!


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## unitednations161 (Mar 13, 2011)

So i tried this is two other vehicles, i can not over fill them!!! The gas is going in the car somehow, when i get my oil change imma ask them at dealership is the tanks are really the same!!! I can go alot longer on the extra gas


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## davhamm (May 2, 2011)

unitednations161 said:


> So i tried this is two other vehicles, i can not over fill them!!! The gas is going in the car somehow, when i get my oil change imma ask them at dealership is the tanks are really the same!!! I can go alot longer on the extra gas


They are the same size tank, read my longer post (#105) above.


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## CRUISE-CRUZE (Nov 8, 2010)

I tried to overfill my ECO MT. No chance! Over the last weekend I had a rental, another Cruze LT with auto transmission. I could put 15.3 gallons. With a bit gas left I think it match the spec.


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## Gunrunr (May 9, 2011)

*On-Star MyLink*

Does anyone use the OnStar MyLink app on their phone to check out their fuel level? I have an Eco model Cruze and my OnStar app tells me that after every fill up I only have 11 gallons and that my fuel level is only 90%. This goes with your argument that it does in fact have a bigger tank. It kind of sucks because that means my gas figures will always be off. I would like to know if anyone else has come across this because I have just read this entire thread and no one has brought it up.


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## Quazar (Apr 28, 2011)

I read a blog somewhere that said they confirmed with GM that the A/T version of the Eco has a 15.3 gallon tank, and the M/T version has the 12.6

One thing to remember is that capacity is not based on actual size, it is an average number based on multiple fill ups. There is alway extra head room in a tank.


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## Gunrunr (May 9, 2011)

My Eco is a M/T model so it has to have the smaller tanks either way. I'm just wondering if anyone else uses the app and if their numbers are off also. If a Cruze owner with the "larger gas tank" can fill up his car and his OnStar phone app tells him that he is at 100%......then that would explain a lot. That tells me that my tank is in fact larger and that my fill ups are being cut short by some evil means. I am tempted to try to get another gallon in there and see if my fill percent can get over 90% on my app.


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## 88ls1blazer (May 3, 2011)

well, I must say, i thought you were all crazy, but I just put 15.1 gallons in my manual eco... took forever, but it did it. and definitely did not siphon anything out i filled it so the fuel was always in plain sight, holding the fuel filler at the very lip of the filler neck so it was never possible to siphon...


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## Quazar (Apr 28, 2011)

88ls1blazer said:


> well, I must say, i thought you were all crazy, but I just put 15.1 gallons in my manual eco... took forever, but it did it. and definitely did not siphon anything out i filled it so the fuel was always in plain sight, holding the fuel filler at the very lip of the filler neck so it was never possible to siphon...


Actually this probably confirms it has a 12.6 tank more than anything. I am pretty sure you could get 16 - 17 gallons into the 15.6 tank if you tried. 

From what I originally understood, the 15.6 tank wouldn't fit into the eco, it wasn't just a weight think, is was the combination tank/rear suspension. Though I cant find anything to confirm that.

Remember 12.6 or 15.6 is not the max the tank can hold, its the average fill up amount of gas. Something similar to one click and stop.


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## 88ls1blazer (May 3, 2011)

Quazar said:


> Actually this probably confirms it has a 12.6 tank more than anything. I am pretty sure you could get 16 - 17 gallons into the 15.6 tank if you tried.
> 
> From what I originally understood, the 15.6 tank wouldn't fit into the eco, it wasn't just a weight think, is was the combination tank/rear suspension. Though I cant find anything to confirm that.
> 
> Remember 12.6 or 15.6 is not the max the tank can hold, its the average fill up amount of gas. Something similar to one click and stop.


what? have you ever tried to overfill a car? every other car I own I cannot do this, the tank stops letting the fuel enter after a certain point. this would drink it down every time. My car had almost 60 miles left until empty, stating it had a little over a gallon left in it when I filled up...


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## limited360 (May 6, 2011)

88ls1blazer said:


> what? have you ever tried to overfill a car? every other car I own I cannot do this, the tank stops letting the fuel enter after a certain point. this would drink it down every time. My car had almost 60 miles left until empty, stating it had a little over a gallon left in it when I filled up...


It is a 15.6 gallon tank. 12.6 is forced by a choke in the filler neck (was explained this way to me). It was made 12.6 in order to hit a specific vehicle test weight.

That is what I heard.. :signs013:


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## Quazar (Apr 28, 2011)

I have the NL6. Interesting....

Yes I have overfilled gas tanks before, there are whole threads on forums with questions on if this is harmful because some people intentionally do it.

In any case, I was looking at the RPO codes for the cruze, two things I noticed.

1. There is only 1 RPO code. 
2. It states only 13 gallons.

I know GM has RPO codes for additional capacity, if you look at their tanks, not all tank sizes are covered. They use RPO of +1, +3, ect in combination with tank RPO.

Tank capacity is not set, as I have tried to explain, its based on average fill up. Changing the pour spout location, the type of pump/filter in it, the design of the float, allowed vapor space, ect can all impact the capacity, and how much overfill it can take. Here is a good article to explain. http://www.oregon.gov/ODA/MSD/docs/pdf/fuel_tank_cap.pdf?ga=t

But I am curious, gas tanks are not that heavy, in fact, a few gallons is heavier than the talk usually. GM would have saved weight by just restricting the flow, but if so, you would be able to overfill it if you took the time to do so.


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## gfxdave99 (Feb 26, 2011)

I have an eco 6mt and have thought that my gas tank is advertised. I have been able to slowly slowly slowly click in more gas but never more then an extra gallon :sad010:


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## lre107 (Nov 4, 2010)

I haven't posted in awhile, but this is an interesting thread. I sometimes use www.gmpartsdirect.com to look up and order parts. Their catalog only shows one fuel tank for the Cruze. I was wondering if maybe there was something different about the filler neck, but the catalog only lists one as well. It is possible that their online catalog hasn't been updated yet with Eco model specific parts, but it does show the Eco wheels and a few other Eco only parts like the grill shutters and actuator. 

Tomorrow I will go to my local Chevy dealer and see if I can get some part numbers.


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## Quazar (Apr 28, 2011)

lre107 said:


> I haven't posted in awhile, but this is an interesting thread. I sometimes use www.gmpartsdirect.com to look up and order parts. Their catalog only shows one fuel tank for the Cruze. I was wondering if maybe there was something different about the filler neck, but the catalog only lists one as well. It is possible that their online catalog hasn't been updated yet with Eco model specific parts, but it does show the Eco wheels and a few other Eco only parts like the grill shutters and actuator.
> 
> Tomorrow I will go to my local Chevy dealer and see if I can get some part numbers.


I went to look as well, I did notice *5*) W/o eco W/o eco Left. The left and right strap specify this. Going to look at my tank now.


.... back. 

So I looked at my tank, kind of difficult, but I went back to the site as well.

There are 2 different sets of straps for the cruze to hold the tank listed on the site. There are also 2 different fuel pumps, one with 13 gallon and one without. 

The straps may have to do with the underbody, the pump could read full sooner.


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## Quazar (Apr 28, 2011)

Went to the dealership tonight for my first oil change. I decided to check out the LS carefully and see the differences.

Looked up under the car, and the gas tank looks bigger. It is a little difficult to tell because the Eco is covered up a lot more. However, the straps and tank look longer.

Also noticed the rear drums are different sizes.

Also, the front grill is more open on the LS, so those plastic back plates on the top grill are differnt for the eco and non eco.


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## davhamm (May 2, 2011)

*Hello*

Really guys, I know from your perspective I am just some new member who may not know a darn thing. 

I had to delete a previous post with ideas on how one could convert their fuel pump module to get more gas in the tank of an eco cruze. 

But if you go read my earlier post and understand fuel system parts, It should be fairly easy to figure out. 

But lets be clear.... THERE IS ONE TANK for the Cruze, there are two Fuel Pump Modules.


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## Big Tom (Mar 8, 2011)

davhamm said:


> Really guys, I know from your perspective I am just some new member who may not know a darn thing.
> 
> I had to delete a previous post with ideas on how one could convert their fuel pump module to get more gas in the tank of an eco cruze.
> 
> ...


I would like to know how to get 25 gal in my tank. When I travel I see gas $.50 to $.90 cheaper than around home and would like to take advantage of that.


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## Quazar (Apr 28, 2011)

davhamm said:


> Really guys, I know from your perspective I am just some new member who may not know a darn thing.
> 
> I had to delete a previous post with ideas on how one could convert their fuel pump module to get more gas in the tank of an eco cruze.
> 
> ...


Actually, to be clear.

There are a lot of parts that are different on the Standard and Eco version that are not listed yet. To say the tanks are the same is not accurate.

IE. -- The rear drums and shoes are different, but not listed.
-- The block offs for the upper grill are different, but not listed. (the eco plasitc back panel on the upper grill blocks 2 more sets of honey comb rows then the standard cruse does.)
-- The tank straps to hold the tank up are different and listed as such.
-- The rear seats are different, and no listing yet for eco version.
-- Rear suspension is different and no listing for eco version yet.
-- The transmissions are different, and not listed yet.

For the M/T eco, the tank looks different. I went to the dealship and looked as best I could. Its a bit difficult without being able to jack the car up and measure.

The tank for the eco is actually the 13 gallon (approx) tank gm has. I have a feeling its similar to the 13.1 gallon on some of the Cobalts. This means, from completely empty its probably a 13.6 (in that range) volume tank with another gallon+ in the fill tube. Which means you could potentially put almost 15 gallons in it. 

The 15.6, completely empty can probably take 16.6 - 18 gallons. So unless eco owners are filling their tanks to overfill with 16.5+ gallons, I would say it is more likely the tanks are indeed different.

Also, the stop or choke, would most likely be located at or on the fill tube and would have nothing to do with the pump itself, as the pump is located about a foot from where the gas enters. Once again, there is no listing for a choke part yet.


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## DJ Ice (May 28, 2011)

Manual Eco should be 13 gal, automatic eco is a 15.6


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## usaalways (Mar 29, 2011)

These are great arguments and I appreciate all the responses and feedback thus far as I am the original poster here...
I now think we really need to call GM and interview someone and post it on YouTube so we can get a definite answer
Cheers! ..and still lovin my Taupe Gray ECO manual with new fog lamps installed


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## davhamm (May 2, 2011)

Quazar said:


> Also, the stop or choke, would most likely be located at or on the fill tube and would have nothing to do with the pump itself, as the pump is located about a foot from where the gas enters. Once again, there is no listing for a choke part yet.


This is not how a fuel fill / shut off works. 

I would suggest you google evap systems, and read up. 

This is for a different car but read this and you will see how Ford does it. 

ALLDATAdiy.com - 2001 Ford Escort ZX2 L4-2.0L DOHC VIN 3 - Evaporative Emission Systems


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## Quazar (Apr 28, 2011)

davhamm said:


> This is not how a fuel fill / shut off works.
> 
> I would suggest you google evap systems, and read up.
> 
> ...


Thank you for that, and the explanation.


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## jan (Apr 16, 2011)

GSDB said:


> I still like mine the bestest, Online conversion of weights and measures, measurement conversion..


Sorry, but your site is ugly, slow and full of irritating clicks and commercials. I've seen a lot of conversion sites and nothing beats http://convertking.net. It is fast, clear and very reliable. And did you see their options? You can change thousands- and decimalmark to everything you would like it to change to. Very neat for pasting into, for example, excel.


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## Boost (Aug 13, 2011)

I am looking at the stock calibration files of a '11 Eco manual and '11 LT automatic with EFILive. Three tables relevant to this topic are very different in the two vehicles' Engine Control Modules:

*F0504* "Primary Fuel Tank Size" _by 4.509804%_ (12.7 <-> 15.7)

*F0513* "Combined Fuel Tank Capacity" _by 4.822304%_ (12.6 <-> 15.9)

*F0505* "Primary Fuel Tank Sender Calibration" _by 2.781863%_

(Calibrates the primary tank fuel level sender to an actual fuel volume level.)

For you local guys to whom I am able to offer my legendary tuning services ,
I would easily and gladly be able to alter these settings if in the future it becomes necessary for some reason. Maybe it will become a popular mod to make all Ecos 15+ gallon, and software calibration will be required


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## SeanM402 (Aug 8, 2011)

70AARCUDA said:


> ...read about the EPA pump fuel/vapor "recovery" requirements.
> 
> ...it's especially "invisible" in CARB land because the huge accordian collars hide both sound and smell from you...and all feel of fuel being siphoned back to the tank.
> 
> ...



What if they dont have the "huge accordion collars" on the nozzle? I live in WI and my job requires me to travel 98% of the time through WI, MN and MI. I have only found 1 gas station with the "collars" on the nozzle.


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## NBrehm (Jun 27, 2011)

I gave up on reading this whole thing but I only have 2 things to say

#1: How do you guys know you aren't pumping a buttload of fuel into your evap system? It's all find and dandy they use the same tank but since you haven't seen INSIDE the tank how do you know it isn't different? There are 2 different fuel pumps and senders listed on the parts list, one for 13 gallon and one for "not" 13 gallon, if the tanks were identical they would be identical and not have different parts.

#2 Except for really long road trips why would you want to? As it is now it takes me about a week to burn through a tank. The only difference you will get is a slight reduction in gas mileage (barely tangible I'm sure, but it WILL be there) and without knowing where that fuel may be back flowing too I am gonna stick with what the manufacturer tells me until I see inside a tank. 

There is no benefit to them doing this. I mean someone brought up highway safety but most of the hybrids and diesel cars can go well in excess of 400 miles, as can trucks with 35 gallon tanks and I am sure a slew of other cars. I just can't grasp ANY reason why GM would care if you put in 3 extra gallons on an ECO unless they changed something. It just doesn't add up


Edit: Fuel tank straps are different too


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## Boost (Aug 13, 2011)

Nick, I was thinking that may cause a MIL (check engine light). I agree with your second point but whatever the customers demand, that's what we have to try to supply


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## NBrehm (Jun 27, 2011)

But why would a customer demand to not be able to carry 3 gallons of gas? 18 pounds isn't gonna make a tangible difference anywhere except over a loooooong period of time. In my mind there has to be more to it. I am willing to bet it is different and the reason has something to do with the different rear suspension.


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## SeanM402 (Aug 8, 2011)

Gunrunr said:


> My Eco is a M/T model so it has to have the smaller tanks either way. I'm just wondering if anyone else uses the app and if their numbers are off also. If a Cruze owner with the "larger gas tank" can fill up his car and his OnStar phone app tells him that he is at 100%......then that would explain a lot. That tells me that my tank is in fact larger and that my fill ups are being cut short by some evil means. I am tempted to try to get another gallon in there and see if my fill percent can get over 90% on my app.


I just filled my car today and the onstar app says "full". I have an LTZ.


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## NBrehm (Jun 27, 2011)

I thought about this more and another thing to consider is almost all gas tanks will hold more fuel then their advertised size. Designers never jam pack a tank with fuel so it could very well be capable of holding even more then 15 gallons but isn't designed to. You have to leave room for thermal expansion if nothing else. If you jam pack nice cold fuel from below ground into your tank and then park the car shortly after and it is hot you could be in for a nice surprise. Jam pack a ziploc bag with cold water and leave it in the sun and see what happens


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## motorman (Sep 26, 2010)

you have to be careful of over riding the auto shut off as if you over fill the tank it cause the fuel gauge sensor to over run the reader and causes fuel gauge problems. i learned this with my new C-5 back in 97. once i quit over filling the tank after the pump shut off no fuel gauge problems. these new tanks are built over size for vapor control of emissions


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## Mofolicious (Jun 19, 2011)

WHITECO said:


> Hmm this is interesting....only problem is I think it will mess up my tracking with fuelly??
> 
> what you guys think?


My thoughts exactly. I always try to fill up at the same station, at the same pump, and stop when it clicks so I can accurately measure mileage.

I know I won't have the patience to sit there and keep trickling the fuel in. F that.


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## NBrehm (Jun 27, 2011)

I don't see why it would affect fuelly. Miles driven/gallons used will still be the same. As long as you keep overfilling the tank it will be accurate right up to fuel system failure


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## tsc (Sep 11, 2011)

Random observation from a guy coming over from the jeep world for some better fuel economy- I recall some stories about some wranglers that used to have two fuel tank sizes- if I recall there was a hose from the fill to that extended farther into the tank- I don't remember all the details but shortening this hose allowed more of the tank to be filled- don't quote me on this and I could be wrong but I do recall a similar conversation some years back


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## tsc (Sep 11, 2011)

Yes you described what I was thinking- I don't know if thats it- but it would fit with what might cause the gas pumps to shut off.


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## Boost (Aug 13, 2011)

The first one looks like two frogs humping each other lol, very creative though Cuda


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## Gritts (Jan 23, 2011)

NBrehm said:


> But why would a customer demand to not be able to carry 3 gallons of gas? 18 pounds isn't gonna make a tangible difference anywhere except over a loooooong period of time. In my mind there has to be more to it. I am willing to bet it is different and the reason has something to do with the different rear suspension.


 
Look at it this way. If you're the designer trying to lighten the car's weight it's very difficult to find 18 lbs. of sheet metal to do without. In the overall diet for the Eco, this would seem a logical choice.


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## NBrehm (Jun 27, 2011)

If you say so, it is 18 pounds. I see what you are saying but I highly doubt that is the case.


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## Quazar (Apr 28, 2011)

NBrehm said:


> I gave up on reading this whole thing but I only have 2 things to say
> 
> #1: How do you guys know you aren't pumping a buttload of fuel into your evap system? It's all find and dandy they use the same tank but since you haven't seen INSIDE the tank how do you know it isn't different? There are 2 different fuel pumps and senders listed on the parts list, one for 13 gallon and one for "not" 13 gallon, if the tanks were identical they would be identical and not have different parts.
> 
> ...


Here is what was sent to me by a gm engineer.



> Its the same tank.
> 
> The way the gas pump shut off works is that it senses the pressure increase in the tank from the displaced air as the tank fills. Gas goes in Air has to leave. As you fill there is a vent tube that leads to the canister. As you get near full a float raises and blocks the vent tube, the air now has to go up the filler neck, the gas station pump senses this increased air pressure and shuts off.
> 
> The vent tube and float are on the fuel pump module. On the cruze a small spacer was added to the tube so that the float will contact the tube sooner and stop the flow of gas. This was an easy way to save mass.



So why save mass? To improve MPG, and its not the individual mass you need to look at, its the total mass saved on the vehicle. All those 5 - 20 lb changes adds up to 200lbs which adds to a couple mpg increase.

Will overfilling affect Fuelly. Absolutly. Since the fill point will be more arbitrary. Unless you decide to always overfill to a specific amount past first click. I.E. 2.2 gallons of additional fuel, no more no less, every time you overfill past first click.

15.1 - 15.5 gallons would give some people the ability to drive 700+ miles in the Eco, where as it may seem awesome, it is way above any average on any car. Thus it is not needed. As it is, most people get 400 - 550 miles per tank and even that is above average for most vehicles. So save the weight, increase the MPG, reduce emissions due to the increase in mpg, and still provide longer travel distances than most cars = GOOD BUSINESS AND ENVIRONMENTAL decision. Especially multiplied by 100,000's of cars over the life of the vehicle. It may seem like small savings to you, but its 100's of gallons of gas annual from one model vehicle. 

From what I was also told, the straps are different because of the rear suspension.


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## Quazar (Apr 28, 2011)

I noticed just the other day that Shell and BP gas stations in the Detroit area have almost completely switched out their fuel nozzles. (as mentioned before by previous people)

From what was explained to me, as soon as the first click happens, a reverse pump is also activated that pumps all the fuel touching the nozzle back into the holding tank. So if you try and overfill the gas tank, a portion of the gas you are paying for is being returned to the gas station. You may not be overfilling with as much gas as you think you are.


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## gfxdave99 (Feb 26, 2011)

Quazar said:


> I noticed just the other day that Shell and BP gas stations in the Detroit area have almost completely switched out their fuel nozzles. (as mentioned before by previous people)
> 
> From what was explained to me, as soon as the first click happens, a reverse pump is also activated that pumps all the fuel touching the nozzle back into the holding tank. So if you try and overfill the gas tank, a portion of the gas you are paying for is being returned to the gas station. You may not be overfilling with as much gas as you think you are.


That id like proof of


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## So Cal Cruzer (Sep 29, 2011)

Very interesting !!!!!!!!!! I just Got my 2012 Eco and have filled it twice..Cant wait to try this..But being in California, if I spill any the station will probably call Haz-Mat and have me arrrested!!!But thanks for this very cool info...


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## 2012ecoTOM (Sep 3, 2011)

I say fill it up and just get a five gallon container and a funnel and fill away, no reverse suck the gas back into the system crap


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## Boost (Aug 13, 2011)

So Cal Cruzer said:


> Very interesting !!!!!!!!!! I just Got my 2012 Eco and have filled it twice..Cant wait to try this..But being in California, if I spill any the station will probably call Haz-Mat and have me arrrested!!!But thanks for this very cool info...


lmao @ dat


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## Randy_the_Hack (Oct 1, 2011)

FWIW... I don't know beans about the Cruze... but this tank restriction technology (to restrict the amount you can pump in v/s what it will actually physically hold) is not new with GM. A buddy of mine has an older Jetta TDI, and this is one of the first mods TDI owners do to their cars... to allow the additional fuel. I don't know exactly what they do on those cars, but it might reveal the industry technology if you'd like me to check. On a car that routinely sees 50 mpg, adding another gallon or two of fuel make a huge difference in range.

EDIT

Nevermind. I talked with my buddy and they have a specific issue with the Jetta TDI. It's the same tank in the diesel as is in the gas Jetta's and there's a vent button they remove; they call it a "ventectomy". Removing the vent button (which, according to him, doesn't work very well) allows them to squeeze an extra gallon to gallon and a half to the tank... which is a big deal for a 50 mpg diesel. Similar issue, but different problem.


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## Boost (Aug 13, 2011)

Thanks for the info Randy. One of the great things about forums is that we get to learn neat things about our cars me might not know otherwise. Good stuff.


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## oolowrideoo (Mar 2, 2011)

So the question is, can the spacer be removed? If not, it seems a "simple" fuel pump swap would result in increased capacity with no harm done to the vent system. Would love to have an eco and non-eco fuel pump in my hands for evaluation.


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## NewCruz (Oct 4, 2011)

Hi All,

I just purchased a new 2012 M6 Eco Cruz that I’m pretty pumped about. I had read this thread before I bought and mentioned to my salesperson that the eco M6 probably had the same sized gas tank as the automatic. He hadn’t heard that, but the next day when I picked up my vehicle, sure enough, he said there was almost 16 gallons of gas waiting for me in the tank. I’ve driven the car 230 miles and my fuel gauge still says full. I’ve burned 5.7 gallons of gas. My digital readout, after bouncing around between 380 miles and 415 miles left in tank for the first 230 miles, now says 401 and is no longer bouncing around, going down accordingly as I drive. My fuel gauge is a tick below full.


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## Gus_Mahn (Aug 16, 2011)

We've had our Eco for just over a month. It has almost 6000 miles on it, so it would be nice to stop for fuel less. I'm willing to do the work to pull the tank and spend $100ish to buy parts. I have access to a lift and proper tools. It's just a matter of finding the actual differences, and an hour or two of work. 

I'm going to get the VIN off of a '12 Eco Auto on the dealers lot, so the local GMC dealer can look it and figure out the actual difference in parts from mine. As I see it, the only downside is the the miles to empty will be too low when the tank is full of 15 gallons. If it can be done, by cutting or bending something, so the much better. I just wish I had access to parts before taking it apart to see/understand the differences.


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## iKermit (Dec 13, 2010)

I just tried to keep filling even after that shut off went off. And my gas over spilled


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## Dpedraza (Oct 24, 2011)

MaximusPrime said:


> Heh, in NJ we have full serve, so I'm at the mercy at the gas station attendants.


yeah that was weird. I went to get out of my car and the guy said it's against the law for me to pump my own gas... I found it to be weird to have someone to pump my gas....


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## iKermit (Dec 13, 2010)

70aarcuda said:


> ...the "hidden" fuel reserve (15.6 _vs._ 12.6 gal) is _only_ on the *eco m6 *models, not on ls or lt models.


fuuuuuuuuuuuuuuuuuuu


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## weimerrj (Dec 4, 2011)

Eric123 said:


> In Canada we do not have the same style of pump. They do not have this feature. The pump clicks off when it reaches the "47 litre" full mark that the ECO tank seems to have. However I can continue to fill but it drains very slowly in. GM has made this tank seem smaller then it is by constricting the flow into the tank once it reaches the 47 litres and causing the neck to back up and trip off the pump when in fact the fuel in the neck will slowly drain into the tank and you can continue filling. This is why it took me nearly 10 minutes to put in the last 11 litres. If I had a portable can I would have had to just poor it really slowly. I understand how GM did it... I guess what confuses me and everyone else is why. Makes me think the part about restricting how far you can drive between fill ups that a previous poster mentioned may be true.


I suspect that the difference is in the filler neck - it probably sticks into the tank farther than the regular one. Once gas fills the tank to the bottom of the neck, it begins to back up and stop the pump. It would also allow you to slowly fill the empty space via gravity. 

So, the solution could be to replace the Eco 6MT filler neck with another model's.

EDIT: Nevermind - I hadn't read through the whole conversation. It seems that the difference is in the vent, part of the fuel pump. So replacing the whole fuel pump assembly would be the way to go.


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## NeonRyder (Jan 3, 2012)

tsc said:


> Random observation from a guy coming over from the jeep world for some better fuel economy- I recall some stories about some wranglers that used to have two fuel tank sizes- if I recall there was a hose from the fill to that extended farther into the tank- I don't remember all the details but shortening this hose allowed more of the tank to be filled- don't quote me on this and I could be wrong but I do recall a similar conversation some years back


This is correct. The 1991-1995 Jeep Wranglers had an option for a 20gal tank instead of the standard 15gal. The tank was the same, the only differnce was the vent tube in the 15gal models was longer, causing the pump to shut off earlier. It was a popular mod to remove and shorten the vent tube to get the full capacity of the tank. It only took me about an hour to do it.


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## cruze1953 (Jun 30, 2011)

OK the tank can hold 15+ gallons, I removed mine because of a fill problem, always stopped at 9 gallons when dic showed 11+ used had to start/click start click for 10 minutes to reach dic used total. The tank on the eco has 3 different vents, each fitted with a float valve that extends about 3 inches below top of tank, as these close less and less air can get out and finally almost no vent when all 3 are closed, I believe thats the difference between the regular tank and eco tank. I added a 4th vent at the high spot on the fuel pump modual to carbon canister/vapor container and returned it to the small tube going to the top of the filler neck. Next fillup went normal and right past the 9 gallon threshold I had hit before, downside is if it is overfilled to extreme, liquid fuel may get into canister so I am carefull not to go much beyond the DIC used fuel figuire.


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## maven (Feb 27, 2011)

70AARCUDA said:


> ...the elaborate vent plumbing is to: (A) control vapor emissions during filling (EPA mandated) and (B) to ensure adequate fuel remains in tank to "cool" the emersed fuel pump. Just be sure that you don't _"...run the tank completely empty..." _or you _will _be replacing the fuel-pump assembly.



Naahhhh, stuff and nonsense. Besides the fact that if you run the tank completely empty youd be walking, the pump is just fine if it isnt completely covered in fuel, if it was a concern the car would shut off when the ECM sensed fuel level was low enough to reduce the life of the fuel pump, remember GM has to warranty the thing for 100-150kmiles, so if they thought it running low significantly shortened its life you could be sure theyd implement a line of code to kill the pump at low fuel levels.


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## PBMooreInCMH (Jan 1, 2012)

Hello everyone,
2012 Cruze Eco MT. I noticed something strange this morning. When I gas up at Speedway or Giant Eagle, the nozzle only goes in halfway. The back splash guard is no where near my car. Also, the needle on my gas meter just barely goes above "F" and just under the last dash above the F. 
This morning, I gassed up at Marathon and the nozzle went all the way in to where the back splash guard was flushed against my car. Going home, my needle on my gas meter, for the first time since I got my car, went all the way to the final notch above the F. 
I will be getting my gas at Marathon from now on.


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## Jim Frye (Mar 16, 2011)

70AARCUDA said:


> ...unless Marathon is a subsidy of one of these oil companies, you're not getting "Top Tier" gasoline as required by GM:
> 
> 
>   
> ...


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## PBMooreInCMH (Jan 1, 2012)

Looks like Shell is the only one I would be able to go to. But I will stick with Marathon.


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## Jim Frye (Mar 16, 2011)

70AARCUDA said:


> ...page 9-39 of the *2011* Cruze Owner's Manual:_
> _


Thanks. Yeah, I see it and I finally downloaded the 2012 manual too. I love the "advice" of also not using any fuel with MMT in it. They tell the owner to ask the station attendant if the fuel contains MMT. ROFLMAO! Most of the folks that work in gas stations around here can't tell you what the Ethanol level is, let alone what additives are in the tank in the ground. It would be interesting to see what percentage of Cruze owners are really putting "Top Tier" gas in their cars. Given that the nearest Top Tier station to me is 10 miles away, way out of my normal travel routes, and is always 5 to 10 cents a gallon more expensive than others when I do drive by it, I really wonder how many of the over 200,000 Cruzen sold here actually burn Top Tier gas.


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## Jim Frye (Mar 16, 2011)

70AARCUDA said:


> ...sounds like an _excellent_ candidate to be a POLL question here! What do you think?


Done!


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## BJ Cruze2012 (Nov 10, 2011)

It could be that the filler neck extends further down into the tank, so the fuel level hits the bottom of the fill tube "3 gallons fast". Extending the bottom of the tube would have the same effect as moving the vent, without modifying the tank, just making the filler tube longer, (inside the tank).


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## BJ Cruze2012 (Nov 10, 2011)

For those that question WHY we want more capacity, I offer this. My daily commute is just over 100 miles round trip. It would sure be nice to be able to do my work driving without having to add time to my commute one night each week, just so I have enough gas to get to work AND home the 5th day. I could fill while running my weekend errands, and not hassle with filling during my already too long commute time!


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## PBMooreInCMH (Jan 1, 2012)

Well since Shell is the only station in my city that falls under Top Tier and the stations are too far away from me, I will just put a complete fuel system cleaner in my tank when I get my oil changed. I usually do.


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## savethewave (Dec 17, 2011)

For NJ gas purchaser or others, you can always get a gas can filled and top off with the can. There is no bubbling effect when the gas is going in, thus easy to add the 3 gallons.


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## DeeCruze (Jan 21, 2012)

I have a 2012 Eco....Top it off at about 11 gallons and Gas started drippin out the bottom on my foot....so i drove home with the gas smell in the car SMH... maybe they changed the tanks in the 2012's?


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## tedstiles (Mar 24, 2012)

This issue is unbelievable. I never thought this could/would happen. Amazing!! Thanks from an Eco up here in Canada. I'll check this out too.


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## NickD (Dec 10, 2011)

Know for a fact the 2LT has a 15.6 gallon tank. When I read articles on the Eco, they have got to be kidding by using thinner sheet metal, eliminating the spare, saving 18 pounds of gas to reach a number like an overall 65 pound weight savings. Also mentioned changing the ratios of I believe 2nd, and 3rd gear. For a 3,000 pound car, that is only a weight savings of 2%.

And that 2% does not translate into gaining a 2% increase in fuel economy. Wind resistance plays a far more significant factor, but even that is insignificant compared to how you drive it.

Suppose I could drive with only two gallons in my tank, that would save about 80 pounds. But then the life of those crazy fuel pumps would be greatly shortened, they depend heavily on excess gas for cooling.

Major problem is with the EPA specifying over 155 blends of gas, you have no idea of what you are getting. That really affects your fuel economy more than anything. Was very surprised in the 2012 2LT models, could finally get a manual transmission, that cinched my decision for what to buy. With all of this automation stuff, for convenience or whatever, taking away the control you have over your vehicle and turning that over to some geek that writes the firmware. I like being in control.


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## BJ Cruze2012 (Nov 10, 2011)

Taking my car in on Monday. I have discussed this with my local dealer. The service group has ordered a new 15.6 fuel pump, they are going to remove mine, and measure the vent tube on both pumps, and cut mine down to match the one on the 15.6 gal pump. I have asked for them to give me the cut off piece, since I will be paying for this work to be done. I will post pictures and measurements of the piece after the work is done. They verified the pump is the same specs beyond that vent tube. It will be nice to be able to use the entire capacity of the tank without spending an extra 10 minutes on each fill!


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## obermd (Mar 3, 2012)

The weight reductions in the ECO assist in city MPG only. Once on the highway air friction is the biggest factor in MPG.


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## '12Eco (Feb 28, 2012)

BJ Cruze2012 said:


> Taking my car in on Monday. I have discussed this with my local dealer. The service group has ordered a new 15.6 fuel pump, they are going to remove mine, and measure the vent tube on both pumps, and cut mine down to match the one on the 15.6 gal pump. I have asked for them to give me the cut off piece, since I will be paying for this work to be done. I will post pictures and measurements of the piece after the work is done. They verified the pump is the same specs beyond that vent tube. It will be nice to be able to use the entire capacity of the tank without spending an extra 10 minutes on each fill!


Please post the results. I really wish I could go longer than 2.5 days without filling up.


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## BladeOfAnduril (Apr 27, 2012)

BJ Cruze2012 said:


> Taking my car in on Monday. I have discussed this with my local dealer. The service group has ordered a new 15.6 fuel pump, they are going to remove mine, and measure the vent tube on both pumps, and cut mine down to match the one on the 15.6 gal pump. I have asked for them to give me the cut off piece, since I will be paying for this work to be done. I will post pictures and measurements of the piece after the work is done. They verified the pump is the same specs beyond that vent tube. It will be nice to be able to use the entire capacity of the tank without spending an extra 10 minutes on each fill!


Any updates on this?? 

Sent from my Galaxy Nexus using AutoGuide.Com Free App


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## BJ Cruze2012 (Nov 10, 2011)

Sorry, I've been off line for so long gang......The fix the service manager thought he could do, he couldn't......SO, I am still spending the extra 10 minutes per fill up. :angry:


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## kfr291 (Aug 11, 2012)

70AARCUDA said:


> ...you must've "coasted" into that gas station if it "took" 15.622 gallons to fill a 15.6 gallon capacity tank!


these cars are effecint plus the .5 gallon in the fuel lines


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## kobowm (Jan 22, 2013)

I believe it. I just filled mine up today. 2011 eco and I put 15.13 gallons in it. 

Sent from my Galaxy Nexus


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## newsguy99 (May 24, 2013)

OK.. so, I read this over, and wanted to see for myself.. So...
























































First pic.. at the Gas Sation with engine on, ready to exit car. Clearly showing the fuel remaining on the gauge, and what the DIC is saying.
2nd pic.. is miles traveled on this fillup, avg mpg, and mph.
3rd pic.. shows how many gallons of fuel was used
4th pic.. how much gas I just put in the car. And, no, I didn't spill any, and it still wasn't at the lip of the gas cap.
5th pic.. shows how many miles I should be able to get on this tank of gas. Still at the gas station, engine not turned back on.
6th pic.. same thing, maybe a bit clearer.. 
7th pic.. The receipt for my fill-up..
8th pic.. Just showing its a MT6
9th pic.. Just showing its a Eco


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## obermd (Mar 3, 2012)

The ECO MT has the same 15.6 gallon tank as all other retail US/Canada Cruzen. As one of our members discovered, the difference is the fuel pump. The ECO MT's fuel pump has a shroud on the main vent that hangs down far enough to "block" the top three gallons of the tank. Tank sizes are always advertised to the main vent shutoff level and never include the fill pipe. Our fill pipe is about half a gallon.


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## obermd (Mar 3, 2012)

70AARCUDA said:


> *16.1 = 15.6 + 0.5 + ?* ...where *?* = fill pipe and/or evap canister _over fill._


The fill pipe is *about *half a gallon. This doesn't include the capacity of the fuel evaporative catch/control system, of which I have no idea other than it won't be that much.


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## Gus_Mahn (Aug 16, 2011)

There's a valve/float in the tank to prevent the fuel from making its way into the evap lines. I'll try to get some pictures.


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## LS1LOL (Feb 24, 2013)

quazar said:


> here is what was sent to me by a gm engineer:
> 
> "its the same tank.
> 
> ...


dude you are the man, this was practically the only useful post in this entire thread thank you!


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## LS1LOL (Feb 24, 2013)

BJ Cruze2012 said:


> For those that question WHY we want more capacity, I offer this. My daily commute is just over 100 miles round trip. It would sure be nice to be able to do my work driving without having to add time to my commute one night each week, just so I have enough gas to get to work AND home the 5th day. I could fill while running my weekend errands, and not hassle with filling during my already too long commute time!


I am in the same boat bro!


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## LS1LOL (Feb 24, 2013)

I am assuming I would need the middle pump to get this to work? Thanks.


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## labatt50 (May 31, 2014)

humm humm...today i worked on 3 variation of fuel module for the cruze
By the way they are all physically identical* (small difference will be describe)

#1 15.6 gallon
#2 15.6 gallon e85
#3 12.6 gallon


#1 is the regular module
#2 is the module use in the buick verano (but also use in some cruze) it is the same as #1 except the pump is higher spec and electric connector are seal (all because of e85) (from memory wide open flow on this one is 195 liter per hour vs 165 liter per hour, around 3.1bar... i don't recall sorry  )
#3 is same as #1 except the FLVV is much longer (i saw you guy figured that out a long time ago)

I guess... i could get ahold of some regular FLVV only instead of changing the whole fuel module for those who would like to convert their tank....


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## UlyssesSG (Apr 5, 2011)

labatt50 said:


> I guess... i could get ahold of some regular FLVV only instead of changing the whole fuel module for those who would like to convert their tank....


_*labatt50,*_
I just joined the thread so would you tell me what FLVV is an acronym for? Thanks.


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## labatt50 (May 31, 2014)

*Fill Limit Venting Valve

*










this is the eco module... look at the FLVV how low it is









this is the regular module, the flvv is sitting at a normal height


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## Gus_Mahn (Aug 16, 2011)

LS1LOL said:


> View attachment 75802
> 
> 
> I am assuming I would need the middle pump to get this to work? Thanks.


Yes, that seems correct, but why spend that much money? All you really need is the FLVV. Used modules can be had for about $60. Just pull the FLVV and put it on your OE module, and save the Junk Yard module for a spare. These cars are still so new, that there are lots of low mileage used modules out there. Check out eBay and Car-Part.com--Used Auto Parts Market


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## Merc6 (Jun 8, 2013)

labatt50 said:


> *Fill Limit Venting Valve
> 
> *
> 
> ...


Was there a way to only get that part? Would just swapping this cause the car to read full at 11 gallons and stay "full" till you burn down to 10? 



Gus_Mahn said:


> Yes, that seems correct, but why spend that much money? All you really need is the FLVV. Used modules can be had for about $60. Just pull the FLVV and put it on your OE module, and save the Junk Yard module for a spare. These cars are still so new, that there are lots of low mileage used modules out there. Check out eBay and Car-Part.com--Used Auto Parts Market


This was my plan(whole assembly not just the FLVV till now), I just didn't have the space to perform it.


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## Gus_Mahn (Aug 16, 2011)

Merc6 said:


> Was there a way to only get that part? Would just swapping this cause the car to read full at 11 gallons and stay "full" till you burn down to 10?
> 
> 
> 
> This was my plan(whole assembly not just the FLVV till now), I just didn't have the space to perform it.


 It sounds Labatt50 may have a source for the FLVV. As far as I know, no other source other than new or used modules has been found. The DTE is calibrated to 12.2 gallons, so the gauge won't move for 120 miles at 40 mpg or more if the tank is topped off. The gauge needle does go higher on the scale with the 15.6g FLVV than the 12.2 FLVV. My car has the whole 15.6 module, and it's accurate below 12.2 gallons. I'm doing the swap on my other Eco, and I plan on just swapping the FLVV with one off an eBay module.


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## Merc6 (Jun 8, 2013)

When I top off like the 1st post, I read 380 to empty and as I drive it crawls up to about 470 till empty. Truthfully I wouldn't care if it did or didn't read full till 10 gallons as long as I didn't spend all that time trickling the gas in.


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## obermd (Mar 3, 2012)

When the ECO MT is truely full of gas, the needle won't move until 200 or more miles. During that time the distance to empty is pessimistic because the car doesn't really know how much gas in the tank.


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## Merc6 (Jun 8, 2013)

obermd said:


> When the ECO MT is truely full of gas, the needle won't move until 200 or more miles. During that time the distance to empty is pessimistic because the car doesn't really know how much gas in the tank.


Reason I asked if just switching that part would change this vs swapping the entire assembly out from the right year(s)


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## labatt50 (May 31, 2014)

Well... Yes i have acces to FLVV only, but since the company i work for design parts... I would need someone to test it and report to see if it works well as OEM.

I would give one FLVV to a member here. But in exchange he need to take picture of installation and report the behavior of filling the tank at the gas station.


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## Gus_Mahn (Aug 16, 2011)

labatt50 said:


> Well... Yes i have acces to FLVV only, but since the company i work for design parts... I would need someone to test it and report to see if it works well as OEM.
> 
> I would give one FLVV to a member here. But in exchange he need to take picture of installation and report the behavior of filling the tank at the gas station.


Somebody needs to take you up on this! I just put my second one in. I have one car running on a whole 15.6g module and one with the stock module with the 15.6 g FLVV. There's no difference in what I can tell. I will say that Labatt's module looks even shorter than the 15.6g one so you might get a little more in before having to start trickle filling.

BTW my second car said 47 (@40mpg indicated) miles to empty with the stock module when I pulled the tank. When done, I drove 1.5 miles to the gas station and it took 13.4 gallons. So it looks like there should be about a gallon left when the range goes to 0. It's also worth noting the fuel pump must have an internal pressure relief which dumps into the white plastic cup around the pump to keep it cool, because I had to dump out the cup's gas while changing the FLVV. The pump will stay cool until the tank goes empty IMO.


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## BradHerr (Sep 29, 2013)

labatt50 said:


> Well... Yes i have acces to FLVV only, but since the company i work for design parts... I would need someone to test it and report to see if it works well as OEM.
> 
> I would give one FLVV to a member here. But in exchange he need to take picture of installation and report the behavior of filling the tank at the gas station.


I have a diesel ECO and believe it's fuel tank operates the same as gas ECO. When filling the CTD, the pump shuts off around 12-13 gallons (from "low range" on dic) I ALWAYS put 17+ gallons in the car. 
Is it possible that the CTD has the same FLVV? I know the diesel fuel foams more during refueling, but I've trickled the entire first 12 gallons in to the tank to keep the foam down and doesn't make a difference. I can pump it fast or slow and it still stops around the same mark. 
I was just getting ready to drop my tank and see if I could by-pass "a shut-off" until I read this post!
I am very interested to know if I could change my FLVV. I may just go ahead a drop it and look in there. 


-Brad


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## BradHerr (Sep 29, 2013)

Gus_Mahn; said:


> It's also worth noting the fuel pump must have an internal pressure relief which dumps into the white plastic cup around the pump to keep it cool, because I had to dump out the cup's gas while changing the FLVV. The pump will stay cool until the tank goes empty IMO.


I have been saying this since day one. Most people tell me I am going to burn up my pump running the car low on fuel. The return/pressure relief usually dumps right on top of the pump for this reason. I am glad someone else noticed this. 



-Brad


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## Below2K (Jun 18, 2014)

Based on these pictures couldn't you just remove the FLVV spacer (black plastic between the FLVV and top of the module) on the ECO version? Or is the FLVV itself, different?



labatt50 said:


> *Fill Limit Venting Valve
> 
> *
> 
> ...


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## labatt50 (May 31, 2014)

Below2K said:


> Based on these pictures couldn't you just remove the FLVV spacer (black plastic between the FLVV and top of the module) on the ECO version? Or is the FLVV itself, different?


Unfortunatly... It is not a spacer, it is really the top of the FLVV. I thought it was but i found out not


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## Cruzeholio (Mar 11, 2012)

Curious if anyone has found a reliable source for the FLVV. I'm in the same boat with a 12 Eco 6MT...I have found the entire fuel pump unit on ebay for $95 but I'm hesitant to buy an entire unit when I only need the FLVV. Am I understanding correctly that all i need is the 15.6 unit (FLVV is red?) to make this work? I commute 242 miles one way and being able to go round trip without a stop would be amazing. Thanks.


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## money_man (Feb 25, 2014)

I just spent $850 on a sending unit for a savanna van the other day. $95 is laughable


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## Cruzeholio (Mar 11, 2012)

$95 isn't laughable if someone has a $30 fix....congrats on being robbed.


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## Gus_Mahn (Aug 16, 2011)

Cruzeholio said:


> Curious if anyone has found a reliable source for the FLVV. I'm in the same boat with a 12 Eco 6MT...I have found the entire fuel pump unit on ebay for $95 but I'm hesitant to buy an entire unit when I only need the FLVV. Am I understanding correctly that all i need is the 15.6 unit (FLVV is red?) to make this work? I commute 242 miles one way and being able to go round trip without a stop would be amazing. Thanks.


You can find the whole module used for about $60 at Car-Part.com--Used Auto Parts Market or on eBay. Just pull the FLVV out if it, and put it in your module then throw the JY module on the shelf for a spare. I have two spares with my old 12.2 FLVV's on them BTW.

So is Labatt50 out as a source for new FLVV's?


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## money_man (Feb 25, 2014)

Cruzeholio said:


> $95 isn't laughable if someone has a $30 fix....congrats on being robbed.


It's only Americans that think this way. Canadians are just happy to find the part. We don't worry about nickels and dimes


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## Merc6 (Jun 8, 2013)

money_man said:


> It's only Americans that think this way. Canadians are just happy to find the part. We don't worry about nickels and dimes


Lol if we didn't worry about nickels and dimes we'd all be running around in 10 second 8 mpg V8 cars poking fun a Cruze owners acting all smug about getting 30-40-50 mpg 


Sent from my iFail 5s


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## money_man (Feb 25, 2014)

I just find it weird that people worry about a $100 part as important as a sending unit (even if you don't need the whole thing) when I spent $100 on a gmpp exhaust tip for my cobalt without a second thought. It might be because my dad owns a mechanic shop so I know how expensive things are. Average sending unit in Canada is no cheaper than $250, and I've ordered ones for customers worth up to $1700 for a land rover. 

I mean a good quality rotor is going to cost $100


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## money_man (Feb 25, 2014)

I do worry about prices of some things. My 1971 nova ss burns through $40 of 91 octane in about 100km so I don't drive it that much


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## Robbyjarm (May 28, 2014)

You realize you pumped 15.622 into the tank right? Assuming you had .5 gal left that means your total fuel capacity was at 16.122. Well. Considering It's a 15.6 gallon fuel tank, you know where the rest of that fuel went? Straight into your Charcoal canister. Haha oh you. Foolish. NOT WORTH THE EXTRA SPACE.


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## Dragonsys (May 27, 2013)

Robbyjarm said:


> You realize you pumped 15.622 into the tank right? Assuming you had .5 gal left that means your total fuel capacity was at 16.122. Well. Considering It's a 15.6 gallon fuel tank, you know where the rest of that fuel went? Straight into your Charcoal canister. Haha oh you. Foolish. NOT WORTH THE EXTRA SPACE.


actually that extra half gallon goes into the fuel filler neck


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## Gus_Mahn (Aug 16, 2011)

Robbyjarm said:


> You realize you pumped 15.622 into the tank right? Assuming you had .5 gal left that means your total fuel capacity was at 16.122. Well. Considering It's a 15.6 gallon fuel tank, you know where the rest of that fuel went? Straight into your Charcoal canister. Haha oh you. Foolish. NOT WORTH THE EXTRA SPACE.


Actually no. The FLVV is the safety device that prevents this from happening on the Cruze. There was a time when your statement would be correct. There is a substantial history of people topping off their Cruzes (including me)and I've never seen any history of charcoal canister issues on the Cruze.


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## Merc6 (Jun 8, 2013)

Gus_Mahn said:


> Actually no. The FLVV is the safety device that prevents this from happening on the Cruze. There was a time when your statement would be correct. There is a substantial history of people topping off their Cruzes (including me)and I've never seen any history of charcoal canister issues on the Cruze.


I been a year into trickle fill and the worst that happened was gas prices going up. When I trickle I burn it driving 2 states away. I never trickle in the city as I like fresh 93. 


Sent from my iFail 5s


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## Blue Angel (Feb 18, 2011)

money_man said:


> It's only Americans that think this way. Canadians are just happy to find the part. We don't worry about nickels and dimes


I disagree. I think we're just so used to getting screwed for anything automotive we just don't feel it anymore.

Until I moved to Ottawa, an hour from the border. Now I proudly think like an American and save every nickel and dime I can.


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## LS1LOL (Feb 24, 2013)

http://www.cruzetalk.com/forum/34-1-4l-turbo/78769-ls1lols-eco-flvv-swap-thread.html


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## Gus_Mahn (Aug 16, 2011)

Not sure if they'll work for us, but there are Eaton FLVV's listed on eBay​ for about $20 delivered.


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## labatt50 (May 31, 2014)

Gus_Mahn said:


> Not sure if they'll work for us, but there are Eaton FLVV's listed on eBay​ for about $20 delivered.



i'm pretty sure it will work (almost all flvv i work with have the same diameter and the position of the ear seems to be standard)... and you will have more fuel because the window that let the fuel push the valve in the flvv is way higher than a regular cruze (which is higher than a cruze eco)

expect 2-3-4 liter more over a regular cruze flvv


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## obermd (Mar 3, 2012)

labatt50 said:


> i'm pretty sure it will work (almost all flvv i work with have the same diameter and the position of the ear seems to be standard)... and you will have more fuel because the window that let the fuel push the valve in the flvv is way higher than a regular cruze (which is higher than a cruze eco)
> 
> expect 2-3-4 liter more over a regular cruze flvv


With our relatively short fill pipe this may lead to overfill and splash back on high speed pumps.


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## Gus_Mahn (Aug 16, 2011)

Just a little update for the thread. From left to right Eco 12.6 gallon FLVV, Cruze 15.6 gallon, Ebay 17gallon? The 12.6 gallon FLVV hangs 1.6" from the bottom of the fuel pump module, the 15.6 hangs .579" from the bottom of the module, and the eBay FLVV sits flush with the top of the fuel pump module. So simple math is about 3 gallons per inch at that part of the tank. So, the extra .579" on the eBay FLVV ought to get another gallon and a half over the 15.6FLVV.

I have run one tank on the eBay FLVV. Showing 70 miles until empty while averaging 35 mpg, it took 15 gallons before the pump clicked off. It runs fine and the monitors set, but if I do another one, I'll just use the cap off the eBay FLVV on the original FLVV. All the parts of the FLVV's interchange directly, but the float, cup, and spring are different on the eBay FLVV. I may try to call Eaton to see what the original application was.


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## Gus_Mahn (Aug 16, 2011)

I was able to contact Eaton, and *FLVV 20135-A is for a gasoline application. I have 5-6 tanks on the eBay FLVV without issue. Usually I fill up with 1/8 tank left, and it takes about 15 gallons.*


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## XtremeRevolution (Jan 19, 2012)

Amazing. Looks like I'm ordering one of these.


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## XtremeRevolution (Jan 19, 2012)

Gus_Mahn said:


> Just a little update for the thread. From left to right Eco 12.6 gallon FLVV, Cruze 15.6 gallon, Ebay 17gallon? The 12.6 gallon FLVV hangs 1.6" from the bottom of the fuel pump module, the 15.6 hangs .579" from the bottom of the module, and the eBay FLVV sits flush with the top of the fuel pump module. So simple math is about 3 gallons per inch at that part of the tank. So, the extra .579" on the eBay FLVV ought to get another gallon and a half over the 15.6FLVV.
> 
> I have run one tank on the eBay FLVV. Showing 70 miles until empty while averaging 35 mpg, it took 15 gallons before the pump clicked off. It runs fine and the monitors set, but if I do another one, I'll just use the cap off the eBay FLVV on the original FLVV. All the parts of the FLVV's interchange directly, but the float, cup, and spring are different on the eBay FLVV. I may try to call Eaton to see what the original application was.
> View attachment 208586
> ...


Hey, do you have any estimate as to how much empty space (in gallons) exists in the tank after the ebay FLVV is installed?


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## Gus_Mahn (Aug 16, 2011)

XtremeRevolution said:


> Hey, do you have any estimate as to how much empty space (in gallons) exists in the tank after the ebay FLVV is installed?


I've not topped it off since installing this FLVV. I'd guess that it could topped off 1/2-1 gallon.


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## Gus_Mahn (Aug 16, 2011)

XtremeRevolution said:


> Hey, do you have any estimate as to how much empty space (in gallons) exists in the tank after the ebay FLVV is installed?


I did top it off finally. 1.7 gallons from pump click off, so about 1.3 gallons over the 15.6g FLVV, or just shy of 17 gallons without topping. Xtreme did you ever order one?


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## XtremeRevolution (Jan 19, 2012)

Gus_Mahn said:


> I did top it off finally. 1.7 gallons from pump click off, so about 1.3 gallons over the 15.6g FLVV, or just shy of 17 gallons without topping. Xtreme did you ever order one?


Yes, but never had a chance to install it, and then I bought the 124 Spider Abarth so I've had less of an incentive to drive the Cruze. Plus, I work from home full time. 

Soon enough...

Sent from my STV100-1 using Tapatalk


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