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Ask GM Tech (Cam) Your Own Question
GM Tech (Cam)
GM Tech (Cam), Chevy Technician
Category: Chevy
Satisfied Customers: 29428
Experience:  GM Grand Master Technician 2007. 14 years experience.
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2008 CHEVY: DURAMAX..INTERMITTENT..FUEL FILTER..LIGHT COMES..PULL OFF

Resolved Question:

2008 CHEVY C5500 W/DURAMAX .....HAVING INTERMITTENT PROBLEM WITH "CHECK ENGINE LIGHT" THEN REPLACE FUEL FILTER LIGHTS UP.....THEN REDUCED ENGINE POWER LIGHT COMES ON THEN YOU HAVE TO PULL OFF OF ROAD AND SHUT DOWN AND RESTART. FUEL FILTER HAS BEEN REPLACED 4 TIMES IN FIRST 5000 MILES. DEALER SAYS THAT THEY DON'T KNOW WHAT TO DO SINCE THE CHECK ENGINE LIGHT IS OFF NOW AND DRIVING AROUND DOESN'T DUPLICATE THE PROBLEM. IT ONLY SEEMS TO HAVE THIS PROBLEM WHEN THE BUS IS MAINTAINING INTERSTATE SPEEDS ON STEEP HILLS, ETC WITH A LOAD OF PASSENGERS. ONE OF THE CODES WAS P0087. THIS IS DRIVING US CRAZY BECAUSE WE CAN'T DUPLICATE THE ISSUE ON TEST DRIVES. THIS IS A CHURCH BUS, HELP!!!!
Submitted: 7 years ago.
Category: Chevy
Expert:  GM Tech (Cam) replied 7 years ago.
Welcome. This is a common issue in these engines and they should have no trouble diagnosing this issue. What I suspect is happening is the injectors when they get really hot, like on a long trip start to return too much fuel to the fuel tank which in turn lowers the fuel pressure in the rail. Often the filter is the reason for the low rail pressure. The test that needs to be performed is an injector return flow test but only when the engine is REALLY hot or the results will not lead them in the correct direction.
Customer: replied 7 years ago.
so you are saying to ask them to perform this "injector return flow test" when the engine is hot. Is there anything else that could cause this type problem? I would like to have more than one option to give them in case they say that they have already done this....

Thanks
Expert:  GM Tech (Cam) replied 7 years ago.

Yes, the test is that. I doubt very much that they have done this because the test takes a bunch to set up and do.

The other things to check are the supply lines to make sure they are not kinked or collapsing.

Customer: replied 7 years ago.
ok, one last question. If this "return flow test" shows to be the cause, does this mean simply replacing a injector(s)??
thanks
Expert:  GM Tech (Cam) replied 7 years ago.
This test measures the return flow rate of each injector. If any are too high, then replacing the injector is the repair or injectors is there are several.
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