my car has been having a fuel pressure problem for a while now and I'm at my wit's end. just wondering if you had any insight on the matter.

I've changed the FPR, fuel pump, and fuel filter so far but the problem persists. my fuel pressure when I prime the pump jumps to around 40-43. upon starting the car fuel pressure will settle around 38-39 or so. when cruising fuel pressure will sit at 35~ psi. then when I go WOT the pressure will jump to 43psi but then gradually begin to fall down to as low as 30psi in some cases.

I unhooked the vacuum line on the fpr and fuel pressure jumps to 43~psi and sits which is supposed to be normal for the LT1. when I shut of the car after running for a decent amount of time pressure will drop to mid-low 30's then climb up to about 40psi and then gradually bleed down over a great period of time (over an hour or so)

from my gathering the fpr and fuel pump seem to be operating normal which only leave possibilty of a bad filter or some form of blockage/leak. I did kink the line going to the filter a while back on accident when trying to swap filters out, I did straighten it back out but I feel somewhat of lump on the top. is there anyway to inspect or test the line without further damaging it? I'm worried because there is rubber insulation over the line and I'm unware of the construction so I'd rather be informed before proceeding forward.

 

You need to find out if the line is damaged causing less fuel to move through it than before the damage occured. If all the parts are in good working order it points to a blockage of some sort.

 

unless if there is an opening under the rubber sleeve there shouldn't be a problem, the lines are barely kinked at all

 

I wonder if you have a stuck injector. Have you scanned it yet?

 

well I don't see how a stuck injector would cause that issue unless it being constantly open was draining the fuel rail dry. the car runs great and made great n/a power, doesn't have any running problems just the fp scares me

I'll check that tonight for ****s and giggles

 

ttt

 

If an injector was stuck open, the fuel pressure would bleed off very quickly when you shut the engine down. You've already indicated it seems to hold the pressure for a while, and even increases. I'd be looking somewhere else.

 

any ideas where to poke around fred?

 

If the pressure drops to 30psi under load, there's a problem with the pump, the filter, the fuel pressure regulator or the connecting lines. Hard to narrow it down more than that without checking each component. If you changed the filter, that is ruled out. From your description, sounds like the FPR is responding correctly. A kinked or plugged line may be the answer.

I gather from what you are saying, the problem did not change at all when you changed the pump? When you changed the pump, did you verify that all the connections to the pump were not leaking? Cracked hose or tube????

 

disconnecting the vacuum line from the fpr fuel pressure jumps down to 30psi at wot and breaks up

it's a granatelli walbro if that's worth anything. all connections to the pump and filter are solid. this problem wasn't existant when I replaced the pump, i was having fuel issues on nitrous but it didn't have these problems n/a