erratic needle movement when testing fuel pressure
Thread Starter
Pro
Joined: Jan 2003
Posts: 515
Likes: 3
From: newark DE
erratic needle movement when testing fuel pressure
i recently removed my plenum, runners, fuel rail, and injectors so i could port the TPI intake. while the injectors were out i replaced the orings. i assembled everything and started it up and it ran fine... no audible or visible leaks (fuel or vaccum). however, now when i test my FP, the needle vibrates back and forth, not giving me an accurate reading. my dragstrip performance has also suffered a bit (lost about a tenth and almost 2 mph). before the TPI work, this never happened, and the FP guage needle was always dead on with no movement. what do you think has caused this?
Thread Starter
Pro
Joined: Jan 2003
Posts: 515
Likes: 3
From: newark DE
Re: erratic needle movement when testing fuel pressure (BAM92)
the car was down for about a week. i figured i might have a fuel leak, but i dont smell gas anywhere under the hood. guess ill have to look again
Race Director
Joined: Sep 2003
Posts: 16,836
Likes: 337
From: Database Error Indiana
Re: erratic needle movement when testing fuel pressure (tpivette)
What AFPR do you have ? When I put a JET AFPR on my 86 it did the same thing. I think the adjuster bolt is skinny and moves around. Got rid of it.
Thread Starter
Pro
Joined: Jan 2003
Posts: 515
Likes: 3
From: newark DE
Re: erratic needle movement when testing fuel pressure (Spankyellow)
i have the Holley one. its got a thumbwheel to adjust pressure, not a bolt. the car has never done this before i disassembled the intake. all testing has been with the vac hose disconnected to view fuel pressure at WOT
Team Owner
Joined: Dec 2000
Posts: 90,675
Likes: 304
From: SE NY
Cruise-In II Veteran
Re: erratic needle movement when testing fuel pressure (tpivette)
In that case it sounds like a gas leak somewhere.
Check around the AFPR, front of the fuel rail and check the fuel pressure gauge for leakage. Also verify the gauge is tightly screwed onto the Schraeder.
Check around the AFPR, front of the fuel rail and check the fuel pressure gauge for leakage. Also verify the gauge is tightly screwed onto the Schraeder.
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