# Clocked Wrong or Fuel Sender?



## Goomie (Oct 7, 2013)

Hello. As some of you may already know my fuel gauge does not work correctly in my car. Because of this all of the computers onboard dont work either. Originally I thought this was an issue with the fuel pump being clocked wrong as it was replaced approximately 30,000 miles ago by the previous owner.

Recently, however, I am seeing signs that this may actually be the fuel sender. I was driving on the highway when my guage suddenly dropped to "hello, your gas light is on", even though I still had half a tank of gas (just put gas in the day before). It then went back up when I exited the highway and was cruising at 35 in the city.

Either way this is an expensive fix as the gas tank needs to be removed to get to the fuel pump where it may be clocked wrong or it may need a new fuel sender. The fuel sender part is $30-$45 so if I do not need to buy it, I won't.

Opinions?


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## 70AARCUDA (Nov 14, 2010)

The fuel "float" arm assembly is PART of the fuel pump assembly, "clocking" (mis-installation at wrong angle) is not possible, which points to something else being the problem...ie: bent float arm or defective sweep-resistor (fuel level sensor).

Item #8 in this GM exploded parts illustration: http://parts.nalleygmc.com/images/parts/gm/fullsize/1004281P03-019.JPG

Your dealership should be able to "read" both the resistance value & its ECM-calculated fuel level equivalence via the OBDII connector. What did they find?


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## Goomie (Oct 7, 2013)

Hm strange. The Chevy dealer told me that clocking was the most likely issue but I have not been back. I dont exactly have a lot of money...but either way it sounds like this is going to be very expensive.


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## NickD (Dec 10, 2011)

Use to use a nichrome wound resistor that was good for the sender, but that was replaced with an inked thick film element, not good. Every time you hit a bump, speed up or slow down, that wiper is jumping up and down and wears grooves into that piece of inked carbon. These thick film resistors cost less than 2 cents to manufacture.

Since there are many sources, no telling how well that wiper was plated, ethanol can really corrode these wipers.

What would make life so much easier for everyone, if when you removed the rear seat cushion, a simple access plate would be installed. Some GM vehicles have this, the Cruze does not, so the tank must be dropped. Loved my 85 Honda Accord SEI for this reason, not only had just a fuel sender in the tank, but an access plate to change it, high pressure fuel pump was mounted externally. But because it was so easy to replace these components, never had problems with that.

With other GM vehicles hanging on all that fuel evaporation crap on the tank, with some, a protective cover, with others the cat back exhaust had to be removed, three rusty fuel lines going to the tank, and the filler tube a mile away also had to be removed, just to get to the tank. And if this happens right after a fillup, really have problems in trying to drain it first.

Then they have the nerve to charge 260 bucks for this POS plastic pump with the sender, but you can buy the sender for 40 bucks. Typically around over a thousand buck job to have it done. Kept an external fuel pump to aid in draining tank, will also need three five gallon gas cans if your tank is full. If I don't break anything, takes about a day.

Ha, thinking about trading my Cruze off when the bumper to bumper warranty runs out, getting too old for these kind of jobs. But have been saying this for the last 50 years. Something else I noted about these new unleaded fuels, they burn your skin like acid, so not a pleasant job to do.


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## sciphi (Aug 26, 2011)

See if the sender is contaminated. Buy a couple bottles of Chevron Techron Concentrate (not the ProGuard) or Gumout Regane fuel system cleaners. Run a bottle in the next two tanks of gas, and see if it makes the problem better. You will need a full tank of gas to do that, and need to fill up when your tank hits half-full. The goal is to soak the sender in cleaning-solution-bearing gasoline for a good long while to clean off any junk that could possibly be on the sender.


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## NickD (Dec 10, 2011)

Worked on my old Continental and 92 DeVille, used that cheaper fuel system cleaner that said on the back, removes varnish deposits. Could get by without a fuel gauge on the DeVille, the fuel digital meter told me how many gallons I used and how many miles I had left. I think the Cruze is the same way as this fuel measuring equipment is independent of the sender. But just didn't like seeing zero on that gauge.

This is what the Cruze fuel pump assembly looks like.

View attachment 42658


Unlike other assemblies with long fuel lines welded to it, short nipples, ideal to change if we only had an access plate.

Another change from the old stuff, 12V to a hot wire gauge to the sender back to ground, simple. These feed into the BCM with a lookup table for more accuracy. Could also be a firmware problem.


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## obermd (Mar 3, 2012)

Although it could be the BCM, since OP hasn't reported any other issues that can be tied to the BCM I think it's the fuel pump fill level float. Take a look at http://www.cruzetalk.com/forum/57-how-library/12035-how-15-6-gallons-into-eco-mt-tank.html for information on how to replace the fuel pump and sending unit. Even if you don't do this yourself you will be able to tell if whomever is doing the work is ripping you off for labor and parts.


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## zr1000a1 (Jan 25, 2012)

It should be mandated that all cars have access panels to the fuel pump! Some Impala's have em in the trunk. My Vibe has one under the back seat, LH sedans from Chrysler had em. Many others have em.
I like this idea:
Cutting an access panel to replace fuel pump.

Try the top tier premium gas from Shell, BP, Exxon, Chevron, Texaco, and add the Chevron Techron concentrated plus fuel system cleaner like has been suggested. The top tier premium usually has more detergents, and Shell and BP are loaded from the last set of tests I could find. A lot of the Texaco's now run Chevron's Techron in it from what I can remember.
A thread that has links to some testing of fuel:
http://www.cruzetalk.com/forum/34-1-4l-turbo/30241-top-tier-fuel-2.html#post469402

Wish you could easily reach up there and check the connections. Seems like a friend had a vehicle for which the fuel gauge would stop responding until he would go down a rough road or 4 wheel drive it a little. Would jar something enough to get it to work again.


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## NickD (Dec 10, 2011)

Think I read that in the Cruze owners manual, or maybe someplace else. But said there are good top tier fuels and bad ones. Guess top tier is not necessarily top.

Only thing I know about what has to be clocked in automotive is the alternator, AC compressor, or a distributor. But what the heck, I am only a kid and still learning.


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