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sprinkles08, ASE Certified Technician
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Experience:  ASE Master and Advanced level certified. Factory trained with 15 years dealership experience
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GM: 2002 Gmc2500 6.6L low fuel pressure sometimes mite run

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2002 Gmc2500 6.6L low fuel pressure sometimes mite run fine for aweek or maybe an hour no fuel in oil 184000 mi well serviced

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Try and take notice of how much fuel is in the tank when this happens. The problem may be in the tank.


When the fuel level is high then fuel will be able to supply the pickup's reservoir from the top, not having to pull through the filter on the bottom of the pickup. When fuel level gets low then fuel can no longer fall over into the reservoir naturally and then fuel has to be drawn through the inlet filter on the bottom. If there is debris plugging this filter then it will cause fuel pressure to be low, worst on heavier acceleration, when the fuel level in the tank gets under about 1/4 to 1/3.

Customer: replied 3 years ago.

IT has 3/4 of a tank it has done it when it was full




How are you determining pressure is low?

Has anything been done to attempt to repair the problem?
Customer: replied 3 years ago.

when it loses power I can stop and bleed the fuel system and it will run fine for a long time or a short time dtc p0087 &p1093 &p1094 come up I have cleaned all fuel lines 2002 GMC 2500HD 6.6L

At what point in the system are you bleeding it?


Are you actually seeing air when bleeding?

Customer: replied 3 years ago.

At the filter housing bleeder screw when it loses power A little air

If there were enough air in the system to cause this then you should be seeing a pretty extreme amount of air there, I don't think you would describe it as a little bit of air.


The injector pump contains a mechanical pump that pulls fuel from the tank and through the filter and then pressurizes it to send to the high pressure side of the fuel system.


Since everything from the tank up to the pump is under a vacuum rather than pressure, it's possible for there to be a pinhole in a line or leak at a connection that is allowing air to be drawn in, and you wouldn't see a leak on the ground or while running. Air in the fuel will cause the low pressure you're seeing, and would account for air in the fuel filter housing. A vacuum test can be done on the supply side of the fuel system to ensure the lines are sealed.


If the lines are ok and the problem isn't in the tank then the problem would have to be the injector pump itself.

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