Fuel pressure regulator problem
need steady fuel pressure
Thread Starter
Instructor
Joined: May 2005
Posts: 234
Likes: 0
From: sidney ohio
need steady fuel pressure
Ok i search every where with no luck. I just got a fuel pressure guage and the stock pump check valve was leaking fuel back into the tank and the fuel pressure at idle ranged from 37 to 42psi needle bouncing like crazy, with vacume 45 to 48 without vacume still bouncing, went through trouble shooting in th fsm to find that out so i replaced it with the 255l pump racetronics kit and heres the info.
pressurizes whe primed KEY TURNED ON 47psi then settles at 42 or 43psi doesnt bleed off for at least 3 days still had 21psi at third day.
with engine running running the needle bounces from 37 to 42 43ish area with vacume, 44 45 to 48 with out vacume, why wont my fuel pressure hold steady
additional info, 86 tpi #24 five-0 injectors all ohmed within each other around 15.....used injector noid light all pigtails-harness checked out checked out.....i appear to have adjustable regulator cause there is a adjustment screw in the top.. didnt do much when i tried to adjust the fuel pressure.runs crappy when first started gets better when it warms up.
pressurizes whe primed KEY TURNED ON 47psi then settles at 42 or 43psi doesnt bleed off for at least 3 days still had 21psi at third day.
with engine running running the needle bounces from 37 to 42 43ish area with vacume, 44 45 to 48 with out vacume, why wont my fuel pressure hold steady
additional info, 86 tpi #24 five-0 injectors all ohmed within each other around 15.....used injector noid light all pigtails-harness checked out checked out.....i appear to have adjustable regulator cause there is a adjustment screw in the top.. didnt do much when i tried to adjust the fuel pressure.runs crappy when first started gets better when it warms up.
Pro
Joined: Nov 2006
Posts: 638
Likes: 0
From: Plano TX
I wish I had the same results with my Holley. The dumb diaphragms kept separating from the metal piece that the spring rests on for me. I went through two of them before calling it quits. The Holley is definitely designed for convenience with the size of that dial. Much easier to turn than sticking a little 5/16 wrench in there and trying to turn a little bolt.
Le Mans Master
Joined: Feb 2006
Posts: 8,753
Likes: 9
From: Louisiana
I've got a Holley as well. Holds steady the whole time on my gauge. Wonder if maybe the fuel pressure gauge as a malfunction. Have you tried a different gauge before taking the plenum off to check the FPR?
Thread Starter
Instructor
Joined: May 2005
Posts: 234
Likes: 0
From: sidney ohio
thx for the replys guy, i guess ill be buying a new afpr probably holley..../. it cant be the pulsation dampner the raacetronics kit replace it with a high pressure hose....plus it did it before the kit was installed.....ill let you guys know how it goes
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Acct suspended by request 12 Dec 2012
Joined: Sep 2007
Posts: 94
Likes: 1
From: Louisville KY
Pressure Leak Down?
I have steady fuel pressure while running at all conditions, but the pressure will leak down to almost zero within about 2 minutes of turning the engine off. Is that normal or is the system really supposed to hold pressure indefinitely? If it leaks down and is not supposed to, what problems could that cause?
Thanks!
Thanks!
Burning Brakes
Joined: Apr 2005
Posts: 973
Likes: 0
From: Chico California
Minutes ago I just posted a question asking the same thing. How long does the fuel pressure hold with the engine off? Or, how long should it hold if all things are as they should be, ie; working correctly.
Thread Starter
Instructor
Joined: May 2005
Posts: 234
Likes: 0
From: sidney ohio
ecs what-whos that....... fyi fuel pressure should hold at least overnite....
Causes of a leak down...
faulty fpr
leaky injectors
leaky or faulty cold start valve
leaking pulsation dampner
faulty check valve in fuel pump
a leak down of two minutes is probably check valve or pulsation dampner-dampner can be replaced with high pressure hose and a couple of hose clamps hope this helps
Causes of a leak down...
faulty fpr
leaky injectors
leaky or faulty cold start valve
leaking pulsation dampner
faulty check valve in fuel pump
a leak down of two minutes is probably check valve or pulsation dampner-dampner can be replaced with high pressure hose and a couple of hose clamps hope this helps
Le Mans Master
Joined: Feb 2006
Posts: 8,753
Likes: 9
From: Louisiana
I have steady fuel pressure while running at all conditions, but the pressure will leak down to almost zero within about 2 minutes of turning the engine off. Is that normal or is the system really supposed to hold pressure indefinitely? If it leaks down and is not supposed to, what problems could that cause?
Thanks!
Thanks!
