FPR Problem?
Thread Starter
Racer
Joined: Dec 2004
Posts: 427
Likes: 0
From: Albuquerque New Mexico
FPR Problem?
Okay guys, next step in this heartbreaking month.
Fuel Pressure is coming on initially at 50 psi when I turn the key. Before I start the car it drops again to 38 and then SLOWLY climbs all the way to 46. Now the median fuel pressure witnessed here is within spec, but it is lower than it used to be by alot. (Used to witness 43+ fuel pressure with engine running and 46 at key turn). The FPR is making a swishing sound and I discoverd a very very small amount of wet gas on the nipple of the FPR yesterday.
Does this reek of FPR failure? any other suggestions?
-dave
1996 LT4/Forged 383/Procharger
Fuel Pressure is coming on initially at 50 psi when I turn the key. Before I start the car it drops again to 38 and then SLOWLY climbs all the way to 46. Now the median fuel pressure witnessed here is within spec, but it is lower than it used to be by alot. (Used to witness 43+ fuel pressure with engine running and 46 at key turn). The FPR is making a swishing sound and I discoverd a very very small amount of wet gas on the nipple of the FPR yesterday.
Does this reek of FPR failure? any other suggestions?
-dave
1996 LT4/Forged 383/Procharger
Last edited by drochau; Jul 8, 2005 at 12:59 PM.
Thread Starter
Racer
Joined: Dec 2004
Posts: 427
Likes: 0
From: Albuquerque New Mexico
Okay, I must have been crazy because I cannot find fuel on the FPR nipple now. Please help me out y'all, now I have fuel pressure right up until WOT, this is WHILE DRIVING ONLY. I cannot get the fp to drop while in the garage. GRRR What could this possibly be? FP seems fine otherwise until WOT and full boost. Then the fp drops and the car shuts off. With the turn of the key to off, and then on again the fuel pump comes on, pressures the line and she starts right up. 
Drifting
Joined: Mar 2005
Posts: 1,923
Likes: 0
From: GA
What size injectors? just a shot in the dark, but if it only happens at WOT & full boost...maybe they are going static (open all the time), this will effectivly kill your pressure. or possibly the pump can't keep up with the demand at WOT.
Thread Starter
Racer
Joined: Dec 2004
Posts: 427
Likes: 0
From: Albuquerque New Mexico
Changed the pump three days ago.
Injectors are huge (42 I believe), but there was no problem keeping up with demand before I started having issues. This problem came on about three weeks ago and I've been fighting (seemingly) multiple failures ever since.
-dave
Injectors are huge (42 I believe), but there was no problem keeping up with demand before I started having issues. This problem came on about three weeks ago and I've been fighting (seemingly) multiple failures ever since.
-dave
Race Director
Joined: Sep 2000
Posts: 17,298
Likes: 32
From: The Top of Utah
Most vacuum referenced fuel pressure regulators aren't built to deal with a positive pressure in the vacuum line. Disconnect and plug the vacuum (?) line to the regulator. You can adjust the fuel pressure as necessary, but go make some WOT runs with the fuel pressure gauge hooked up. If the fuel pressure drops, SOMETHING in your fuel system can't keep up with the demand. Otherwise, you may need a different regulator, better equipped to handle positive manifold pressure. MAYBE?
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Thread Starter
Racer
Joined: Dec 2004
Posts: 427
Likes: 0
From: Albuquerque New Mexico
changed the pump two days ago. Old one was I think a stocker(said AC on bottom and was beige in color). Now I have manyh mods including bigger injectors, but starving for fuel was never a problem previously(a month ago).