s1ngle

iTrader: (1)

as the title says, and I'm wondering what is supposed to happen. Mine falls maybe a psi or two, but then just jumps back and forth, it used to rise with my stock injectors and pump. Now I have a walbro 255 and dsm 450's.

thanks!

s1ngle

iTrader: (1)

new development, when i start my car my fuel pressure is fine, although it gets lower when i rev like i said. I drove to work and checked it after I got here, and the fuel pressure is 10 psi lower!!! i know thats not supposed to be happening!

think its my fuel pump?

Turbowa

What kind of FPR do you have?

s1ngle

iTrader: (1)

B&M... and one more weird thing about my fuel system... it doesnt hold pressure for very long at all after I shut it down... the pressure almost immediately falls to 0..

so let me sum the problems up:

1. when i rev fuel pressure falls
2. after driving static fuel pressure is 10 psi lower
3. system doesnt hold pressure.

what could be wrong, where should I start?

Tchleung

what's your idle fuel pressure at with vacuum line on? Mines always dropped a few PSI as well whenever I reved it, but I found ot if I'm higher then 42psi at idle it doesn't do it. anything under it will. also running B&M/walbro/450's. I swapped to a OEM FPR and it deos the same thing because idle fuel pressure on those are even lower then that. I've jsut kept my idle fuel pressure higher then 42ish and it's been fine for a long time. and it's fine that you lose fuel pressure after shutting car off. miens slowly drops after I shut it off as well, it's a common thing from what I've read with aftermarket fuel pumps etc.

s1ngle

iTrader: (1)

thanks Tchleung for your reply,

let me clarify a few things. the LOWEST i have been able to get my fuel pressure to this point is 50 psi (due to the fpr's inability to handle that much pressure, i know i can fix this with a mod on endyn's site) so when i rev, it goes to about 47-48 and jumps back up to 50.

how quickly does your fuel pressure drop to 0? mine is so fast that i jump out of the car after i shut it off, run right to the fuel gauge, and by then its almost at 0. I'm not so worried about that.

the thing i'm worried about most is why, after driving the car 10 mins, does the idle pressure go from 50 to 40. if i shut it off, wait a while, and turn it back on, fuel pressure is at 50 again.

Turbowa

Its very possible that you have a bad fuel pressure regulator. You may want to switch it out with a known good one and see what happens.

s1ngle

iTrader: (1)

yeah, might not be a bad idea... now to get my hands on a known good one.

I think I may also switch back to my stock fuel pump to see if the walbro is the problem.