Ok having a little trouble. Pick up a fuel pressure tester. When i start engine it goes right up to 40 psi exactly. When i gove it gas it drops a couple of pounds but returns to 40psi. Engi e struggles whn giving it full throttle like getting on freeway or climbing hill. I got codes 44 and 45. Is this a pump issue or regulatir possible injector issue?

 

If the pump and FPR are operating properly the rail pressure should RISE when the throttle is opened, not fall. Is the inline filter clean?

 

Yes i changed the filter before test i was hoping that was the problem. Runs decent just cant take full throttle starts to studdder.

 

That sure sounds like a fuel pressure regulator. ....I mean vacuum will cause the reg to raise the pressure. It's not a real complex part. I can't see how vacuum from acceleration could NOT increase pressure, provided the FPR is working properly.

 

Ok to add progresss on problem. They are both bad. Idle would get riugh at cruising speed 30-45 range. Replaced fpr took for test drive 30-45 smoothest ride ever. But i hooked up the gauge and wired to my hood scoop so i can watch while driving. At high speed pressure would not build. At 60mph i would give it full throttle car would studder and not pick up speed quickly and gauge would hit 43psu then go crazy bouncing between 38-45psi quickly and it seemed in sync with the studdering.

Question can i out an inli e pump with old pump still in tank but disconnected? I will be going to a friends house using his lift so can drop tank. I just dont want to buy a new in tank fuels pump as i have no future plabs for one. I will be using a inline pump. Just wondering for now if i can just put the inlibe on and go. Will be parking it in next couple of months if i get a truck for work and will begin stripping down for rebuild. But need to get to work to get down payment for truck. Just want to limit the money going into it since im not going to be usung any of the stock fuel parts in future going for ls swap.

 

Also with vacuum line off fpr fuel pressure only rises to 45psi. And stock pumps at orielly say they have max of 51psi.