I have a 2003 gmc 2500hd that has what I assume is an air in fuel issue. The truck has 146000, new injectors before I bought it, and airdog lift pump. Im not sure if the filter housing is the original or not but it does have a ppe bleeder screw. The problem I am having is the truck started stumbling under heavy acceleration and then started stumbling under normal driving. After I stopped it was hard to restart and then shut off after a few seconds. I replaced the engine fuel filter and primed the system. Idled fine and drive for a short distance and cut off again. Primed the system a few times and limped it back home. No codes are known at this time and no check engine light coming on. I'm thinking that I have an air leak somewhere because the engine won't hold a prime. Any thoughts about where to start looking? I'm going to try to find someone in town with the airdog filters tomorrow as they look like the originals and I'm not sure of their age.

 

If you have a lift pump then you shouldn't have any air entrapment issues. start with good filters first, then move onto the more expensive things if it doesn't resolve.

-bad lift pump or no power
-possible fuel line collapse
-bad regulator or CP3
-high injector return rates

all of these could make for a hard to start or rough running engine