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Chris (aka-Moose)
Chris (aka-Moose), GMC Technician
Category: GMC
Satisfied Customers: 47671
Experience:  16 years of experience
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Wont start!! it cranks, 2002 gmc sierra 2500 hd new injector

Customer Question

wont start!!
JA: Have you checked the battery, particularly the terminal connections? Are they corroded?
Customer: it cranks
JA: What is the model/year of your GM?
Customer: 2002 gmc sierra 2500 hd new injector new pump
JA: Are you fixing your Sierra yourself? What have you tried so far?
Customer: I put a fass 150 lift pump. rebuilt the filter head. new fuel filter new injectors and new cp3 Cranks at 180 rpm and I only get 1.2kpsi rail pressure
JA: Anything else you want the mechanic to know before I connect you?
Customer: nope
Submitted: 2 months ago.
Category: GMC
Expert:  Chris (aka-Moose) replied 2 months ago.

Welcome, I'm Chris (aka Moose). I'm here to help 365 days a year, but not every hour of the day. I try to prevent delays as much as possible. Please understand I am not there and can only advise based on what you tell me. Let's get started.

You mentioned you get 1.2kpsi is that 1200 psi?

Customer: replied 2 months ago.
1200 to 1300 psi at crank
Expert:  Chris (aka-Moose) replied 2 months ago.

Can you do these tests and let me know the results.

Please make sure to rate my answer prior to logging off, as this is how I get credit for helping you. If you have not yet received 5 star excellent service from me. Please follow up so you get everything from me that you expected from the deposit you have already paid, which I get nothing of till you rate me. Rating does not close the post nor prevent replying at a later date.

Thanks Moose

Customer: replied 2 months ago.
desired fuel pressure is 6000 actual is 12-1300. I will check voltages tonight. when its cold it has an easier time starting but still long crank times
Customer: replied 2 months ago.
I will check voltages tonight.. fuel volume return is within spec
Customer: replied 2 months ago.
cylinders 1,2,4,5,6,8, balance rates are all +/- 1 but 5,7 are -3.5
Expert:  Chris (aka-Moose) replied 2 months ago.

Once it starts are cylinder 5 and 7 weaker than the rest?

Customer: replied 2 months ago.
They are actually more powerful and the injector is retarding fuel
Customer: replied 2 months ago.
All voltage tests stayed above 10vt during crank at the fuses... what else needs to happen during crank in order to command the injectors to fire???
Expert:  Chris (aka-Moose) replied 2 months ago.

For an injector to work the FICM sends them constant power and a pulsing ground signal.

Customer: replied 2 months ago.
I understand that but during cranking I know fuel pressure needs to be at a certain amount before they fire... what's else prevents the injectors to fire?? What other conditions need to be met?
Customer: replied 2 months ago.
Or any conditions that need to be meet before it will command higher rail pressure during cranking??
Expert:  Chris (aka-Moose) replied 2 months ago.

As long as the injector pump and FICM works right and the pressure regulator is working and reading right. An accurate cam and crank sensor reading should be all you need.

Customer: replied 2 months ago.
New pump with new regulator installed when running desired and actual match perfectly and no defueling at high RPMs. I also shimed the fuel pressure relief valve
Expert:  Chris (aka-Moose) replied 2 months ago.

I am out of ideas at this point, would you like me to opt out?

Customer: replied 2 months ago.
Expert:  Chris (aka-Moose) replied 2 months ago.

opting out now.

Customer: replied 2 months ago.
Been longer than 24hrs