2003 gmc 2500hd 6.0

[Kaiseraw02]

Hey there,

ive been having some issues with my 2003 Gmc 6.0. I’ve got a code for a p0300. Truck is misfiring on multiple cylinders. I decided to check the fuel pressure on it, and it was at 48psi. When accelerating on the truck it like to bog down in the 2-3k rpm range. The fuel pressure also decreases when I accelerate to about 30psi. I’m aware that these trucks need about 55psi to properly run, but I was wondering if there was anything else I could look into before replacing the pump/filter

 

thanks 

[davester]

The filter is cheap, so if you haven't replaced it recently, might as well change it and recheck fuel pressure afterwards.  Perhaps even cut it open (safely, as it's full of gas, so cutoff wheel on an angle grinder is asking for trouble), and see how the filter looks.

 

After that, I don't know the diagnostic procedure for testing the fuel-pressure regulator (on the fuel rail), but that would be the next thing to check.