Okay so I am having a problem with my fuel pressure bleeding off pretty quick if I let my pump prime. I had a fass 95gph and I noticed it doing this right after I pulled the head and re-installed, installed new 125hp injectors at the same time. Last Friday I put in a fass 150gph just as a upgrade and still doing the same thing.

Basically, I let the pump prime and it builds up to about 15psi then within 3 seconds it will drop 3 psi per second till its back at 0. The truck runs fine and stays around 15psi while driving. I have absolutely no leaks externally. I have a slight hiccup at idle and I'm thinking its either vp44 related or injectors at this point... Has anyone else had this problem?

 

I would say double check for leaks mine was doing this it was the crush washer at the VP and it was seeping very slowly but hard to find but if the truck sat over night the. It would loose prime

 

that's normal...

mine builds pressure while lift pump is running and soon as lift pump stops pumping the pressure drops off a cliff . its just fuel returning through the two return lines. as long as pressure isn't dropping like that while the lift pump is pumping, you're fine.