04 Lb7 won’t start

[dcpjfs432]

Hello everyone, I just installed Injectors in my Lb7 the install went fairly well and I got the truck running after fixing a few fuel leaks. So I ran it around town for 30 minutes starts and stops no problem I got home and shut it off and had to run back to town it started up and I got to town stopped and started no problem and on my way back home it just died and I can’t for the life of me get it running again. I also installed a Air dog lift pump and deleted the stock filter because it was cracked and leaking. I’m at a loss according to my scan tool I’m getting around 380psi at the fuel rail which I know is not enough but I wouldn’t think the CP3 would just go out like that I’ve never had a fuel issue before this. Idk any help would be greatly appreciated. Thanks in advance.


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[ironmax]

What all have you checked or done so far?

 

[gmduramax]

Injectors are bad

 

[ZeroGravity58]

Check and make sure the lift pump is pumping fuel. After that pop off the return line on the driverside valve cover. Crank it over and see how much fuel it is returning. If there is a good amount of fuel you will have to narrow it down to the CP3 or injectors. If there is no fuel being returned then a hose is kinked and the CP3 is not getting enough fuel or the CP3 is trash.

 

[dcpjfs432]

Check and make sure the lift pump is pumping fuel. After that pop off the return line on the driverside valve cover. Crank it over and see how much fuel it is returning. If there is a good amount of fuel you will have to narrow it down to the CP3 or injectors. If there is no fuel being returned then a hose is kinked and the CP3 is not getting enough fuel or the CP3 is trash.

Okay I’ll check that thanks for the input. I did check the lift pump it is working.

The return line is the one on the back of the engine like under the glow plug relay correct?


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[dcpjfs432]

What all have you checked or done so far?

I checked to make sure the lift pump is working and it is so I know fuel is getting to the engine. I haven’t checked the actual fuel pressure with a gauge but after cranking it I pushed the little needle on the fuel pressure test port and I had barely any pressure. I have no visible fuel leaks and there is no fuel in the oil.


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[darkness]

Check that test port with your lift pump running.

 

[dcpjfs432]

Update I checked the test port with the lift pump on and I get good pressure there. But I checked my oil again and I definitely have fuel in the oil. What should I do next??


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[zakkb787]

Could be bad injectors, loose fuel lines, loose or broken return lines

 

[slowlml]

Can rule out the return lines under the valve covers by pressurizing the return line near the gpcm and listen for a leak. its the smaller one. Can pull the pcv hoses off one at a time and narrow it down to which bank is making the noise. Where did you get the injectors from?

 

[dcpjfs432]

Can rule out the return lines under the valve covers by pressurizing the return line near the gpcm and listen for a leak. its the smaller one. Can pull the pcv hoses off one at a time and narrow it down to which bank is making the noise. Where did you get the injectors from?

Okay I will check that stuff. I got remanded Oem injectors I’m kinda regretting not getting bigger ones but I didn’t want to spend crazy money on the truck because it is just a work truck. But If I have to replace them again I’m going to go bigger. The ones I got have a one year warranty.


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[slowlml]

What company did you get them from?

 

[dcpjfs432]

What company did you get them from?

Expressdieselus.


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[slowlml]

Ive never heard of them so i cant comment on the quality. Maybe another member has. It wasnt one of the handful of places that always send out known bad injectors so thats a plus lol.

 

[dcpjfs432]

Ive never heard of them so i cant comment on the quality. Maybe another member has. It wasnt one of the handful of places that always send out known bad injectors so thats a plus lol.

Gotcha well I’m going to do some tests tonight hopefully I can narrow the problem down.


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[dcpjfs432]

Can rule out the return lines under the valve covers by pressurizing the return line near the gpcm and listen for a leak. its the smaller one. Can pull the pcv hoses off one at a time and narrow it down to which bank is making the noise. Where did you get the injectors from?

Ok I pressurized the return line and I can’t hear any leaks so do you think I have a stuck injector?? I’m going to check all the fuel lines to the injectors to see if one of them is loose or something.


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[slowlml]

Try doing a return test on the cp3

 

[dcpjfs432]

Try doing a return test on the cp3

Thanks for all the suggestions everyone!! I figured out the problem I ended up just pulling the pass side valve cover and found one of the O-Rings for the injector lines was messed up. I replaced that and now she’s running perfect and starts right up!!

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[slowlml]

Glad you got it fixed. Thanks for posting what the issue was.