# Cevrolet Cruze 2.0 Z20D1 Crank, no start and fuel flows to HP Pump



## Jakobsson_Linus (Oct 9, 2020)

Hi!
I had to ask you guys since i can't manage to work this out by myself.
I live in Sweden and there isn't that much info on these kind of cars.

My problem is as follows.
I had to lift the top valve cover and replace the gasket. To my inexperience of modern diesel i disconnected fuse 20 to fuel pump as is common on petrol to relief the fuel pressure.

I then disconnected the common rail lines and fuel return lines from the injectors and removed them along with the top cover. replaced gasket and put injectors back along with the fuel lines to the common rail and from the rail to the high pressure pump on the side.

After everything was assembled and all electrical was back in it's place i proceeded to prime the engine by turning the key in on position about then times to allow the diesel to cycle. Then tried to start the car several times with no success.

What i did next was to make sure that fuel was going in to the high pressure pump and it sure does. After that i checked that i had fuel going in the return line, and yes it is flowing.

However i only get a small amount of fuel getting out of the fuel line that goes to the fuelrail, i spits a little with each cycle on the starter. What is the cause to the high pressure pump not building enough pressure?

I have no fault codes or anything, disconnected the electrical connection going to the fuel pressure regulator and made sure that it threw a fault code and sure, code 84 or something showed up. Then reconnected the the wire and the code disappeared so i think that the regulator is working.

But then why would it not build pressure at the rail?

/Best regards Linus


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## Snipesy (Dec 7, 2015)

You should not be touching anything on the fuel rail. Do some studying next time.

Many fuel rail components are one time use. That’s it. You remove it you replace it. Yes that sometimes means spending $100 just to hook up a gauge.

Speaking of gauges. This a high pressure fuel pump. It moves literally mL at a time. So obviously you don’t just see fuel dump out of it.
Consequently even a minor leak drastically reduces pressure building ability.


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## Jakobsson_Linus (Oct 9, 2020)

Thanks for the reply, I know that it's considered to be one time use on some stuff but this isn't something critical since i can replace the entire car for the same price as the replacement parts, i have made sure that it everything is in order and that its not leaking.

So to sum up, since it moves just a couple ml at a time it's normal, i thought it would be a bit of a flow. Guess it can take a little time before the entire system gets pressurized then.


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## Snipesy (Dec 7, 2015)

Jakobsson_Linus said:


> Thanks for the reply, I know that it's considered to be one time use on some stuff but this isn't something critical since i can replace the entire car for the same price as the replacement parts, i have made sure that it everything is in order and that its not leaking.
> 
> So to sum up, since it moves just a couple ml at a time it's normal, i thought it would be a bit of a flow. Guess it can take a little time before the entire system gets pressurized then.


Yes normally we use a 100mL graduated cyllinder to test flow.
The actual space in the high pressure pipes is really small. It doesn’t take very many turns to build starting pressure as the relief control will be closed

Obviously when running it’s higher but some designs will have a bypass on the pump itself so more fuel flows.


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## Jakobsson_Linus (Oct 9, 2020)

I have pressure in the fuelrail and no leaks in any of the connections, but it still wont start after several attempts. Took out the egr and it cleaned it. Still nothing. Im completly lost to what the cause is, only things i have touched is fuel lines to rail, disconnected injectors and fuel returnline. Thats all i had to do when taking off the top cover.


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## Snipesy (Dec 7, 2015)

Jakobsson_Linus said:


> I have pressure in the fuelrail and no leaks in any of the connections, but it still wont start after several attempts. Took out the egr and it cleaned it. Still nothing. Im completly lost to what the cause is, only things i have touched is fuel lines to rail, disconnected injectors and fuel returnline. Thats all i had to do when taking off the top cover.


Do you have a lab scope? Check pulse of injectors.
Did it work before you took off the valve cover?


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## Jakobsson_Linus (Oct 9, 2020)

Yes it worked before removing the valve cover, as soon as i put everything back and primed the fuel it did start for a brief second but since then it hasn't started. Unfortunately no lab scope, i do however get a voltage spike across the injector when measuring with multimeter


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## Jakobsson_Linus (Oct 9, 2020)

Can it perhaps refuse to start if one of the glowplugs is bad? I read that they are supposed to be below 2ohm and 3 of them are between 1.7 and 2 ohms. However glowplug nr 2 are measuring 18ohm so that one is bad for sure. Does the ecu measure the resistance over the glowplug harness and refuse to start because of that?


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## Jakobsson_Linus (Oct 9, 2020)

I have changed glow plug and it now shows the same ohm across all four. I seem to have an issue with diesel pressure. It goes up to 4500psi and drops. And when I turn key to off position it goes down to abou 300psi. Think it could be an issue with the fuel pressure regulator...


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## Ma v e n (Oct 8, 2018)

If you airlocked the return side it won't start, you'll need to pressurize the return side to 500kPa (72-73psi) in order to get things to operate properly.

If you got debris in the fuel rail(easy of you didn't thoroughly clean area before disassembly) it won't start.


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## Jakobsson_Linus (Oct 9, 2020)

I cleaned everything properly before disassemble so I don't think I have any debrie stuck. But how do I go about pressurizing the return side?


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## Jakobsson_Linus (Oct 9, 2020)

Should the pressure in the Fuelrail drop after when the key is in off position?


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## Jakobsson_Linus (Oct 9, 2020)

So this is the pressure when i crank the engine over, still no start. Changed the pressure regulator. My guess is that it could be an injector that back leaks...


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## Jakobsson_Linus (Oct 9, 2020)

Well it all boiled down to worn injectors in combination with bad fuel. I serviced the injectors and put it all together and it now works perfectly. Thought that it might benefit someone else in the future to tell that it was solved.


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## boraz (Aug 29, 2013)

Jakobsson_Linus said:


> Well it all boiled down to worn injectors in combination with bad fuel. I serviced the injectors and put it all together and it now works perfectly. Thought that it might benefit someone else in the future to tell that it was solved.


serviced injectors as in replaced the or


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## Jakobsson_Linus (Oct 9, 2020)

No. serviced as in take them apart, clean, replace faulty parts, assemble and pressure/ flow test.


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## pacolino (Aug 1, 2015)

Jakobsson_Linus said:


> No. serviced as in take them apart, clean, replace faulty parts, assemble and pressure/ flow test.


what faulty parts did you replace buddy?! I'm little bit confused, pls give us some details here, also how did you pressure the fuel rail, you mentioned that you're not able before! How did you flow test is? thx.


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## Jakobsson_Linus (Oct 9, 2020)

The only faulty parts you can replace without having to swap the entire injector out is the needle assembly. I haven't said that i don't have any pressure in the fuel rail. I stated that the pressure was 4500 and even posted a screenshot of the pressure reading if you look in my earlier posts. Not sure what you are asking for here since the post was made to diagnose what made the car refuse to start, not explaining how to service injectors. That is a process witch require special equipment and tools. Flow test are made in a special machine that handle common rail injectors which both pressurize and pulse modulate the injectors to determine function and also checks the fuel return. As to your question on how i pressurize the fuel rail its only a matter of turning the key and crank the engine over so the HPP starts working since it is driven by the camshaft.


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## pacolino (Aug 1, 2015)

Jakobsson_Linus said:


> The only faulty parts you can replace without having to swap the entire injector out is the needle assembly. I haven't said that i don't have any pressure in the fuel rail. I stated that the pressure was 4500 and even posted a screenshot of the pressure reading if you look in my earlier posts. Not sure what you are asking for here since the post was made to diagnose what made the car refuse to start, not explaining how to service injectors. That is a process witch require special equipment and tools. Flow test are made in a special machine that handle common rail injectors which both pressurize and pulse modulate the injectors to determine function and also checks the fuel return. As to your question on how i pressurize the fuel rail its only a matter of turning the key and crank the engine over so the HPP starts working since it is driven by the camshaft.


Okay that's what I thought too, I wasn't sure what parts you were replacing, thx bud.

Sent from my SM-G960W using Tapatalk


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