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Ask GM Tech (Cam) Your Own Question
GM Tech (Cam)
GM Tech (Cam), Chevy Technician
Category: Chevy
Satisfied Customers: 15201
Experience:  GM Grand Master Technician 2007. 14 years experience.
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Chevrolet Silverado 2500 HD Classic LS: I have a 2004 chevy

Customer Question

I have a 2004 chevy Silverado 2500 HD 4X4 crew cab short bed with duramax LB7. truck ran fine but smoke was coming out of pcv tube. It developed a miss at higher rpm like when you romped on it. Checked the refresh rate and were high on all injectors and number 6 injector was bad. Come to find out all of them were leaking compression so installed new cups-injectors high pressure fuel lines-return line banjo bolts and gaskets. It starts and idles fine but when I try run drive normally it acts like it is running out of fuel. Put on computer (low rail pressure). Checked pressure it all seams good until it falls on its face the fuel pressure drops. sometimes it will got to 80 mpa sometimes it goes to 106 then drops to 40-30 mpa. One person says sucking air, one said bad pop off valve or bum injector. shimmed pop off valve , put new rubber fuel lines on. nothing need help don't know what to do next ?????????? KLINT
Submitted: 2 years ago.
Category: Chevy
Expert:  GM Tech (Cam) replied 2 years ago.
Hi Klint, I am Cam. Did you replace all your injectors then or just the cups?
Customer: replied 2 years ago.

all injectors all cups all return line banjo bolts and seals all rubber feed fuel lines.

Expert:  GM Tech (Cam) replied 2 years ago.
Klint, do you have a clear hose to do a test? I would like to have you install a clear hose from the outlet of the fuel filter to the block and see if there are loads of bubbles entering the system. IF so then we still have an air leak, possibly the bleeder valve at the top of the fuel filter head or some connection. If you have no bubbles, then we may be looking at a weak fuel injection pump.
Customer: replied 2 years ago.

I don't have one but can get one tomorrow. if the test is done at idle but it don't mess up until higher rpm or load how do I simulate the conditions.

Expert:  GM Tech (Cam) replied 2 years ago.
Get a longer one and make a loop that can extend up where you can see while driving through the hood crack.
Customer: replied 2 years ago.
sounds good. will try It tomorrow and get back with you.
Expert:  GM Tech (Cam) replied 2 years ago.
How did it go?
Customer: replied 2 years ago.
Relist: Answer came too late.
Expert:  GM Tech (Cam) replied 2 years ago.
Hi there, Did you manage to get the clear hose and see if there were any bubbles?