Fuel Pressure Regulator Help
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Joined: Aug 2006
Posts: 56
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From: Minneapolis Minnesota
Fuel Pressure Regulator Help
I have a 1991 and put an AJ/FPR on it. It will not set, goes to all most 50 and drops right back down. One book says there is an o-ring on one of the inside ports of the regulator / critical . What size? What port should it go on? Car is not at my home so I can't get to it right now to look at it. Thinking we dropped the o-ring out pulling the old diaphragm. OR the book is talking about the two side ports on the hole regulator? WE just took off the top of the regulator not the whole regulator. If not this probable / fuel pump / pulsator? No injector or rail leeks any place. Just will not hold pressure at all. Thanks. 
Team Owner
Joined: Dec 2000
Posts: 90,675
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From: SE NY
Cruise-In II Veteran
When the fuel sustem does not hold prime it can be:
-a line leak
-the FPR leak
-an injector leak
-the pump valve not holding
Did it leak down before you took the AFPR apart?
Had you done any service on the fuel system before the leak down?
-a line leak
-the FPR leak
-an injector leak
-the pump valve not holding
Did it leak down before you took the AFPR apart?
Had you done any service on the fuel system before the leak down?
Last edited by 65Z01; Dec 17, 2006 at 10:55 AM. Reason: added question
Thread Starter
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Joined: Aug 2006
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From: Minneapolis Minnesota
MORE info
<Motorbooks workshop 101 projects for your Corvette 1984-1996> talks about the o-ring on page 62. I don't think they are talking about a fuel rail o-ring but an o-ring that goes over one of the ports on the top/ inside of the FPR.
Team Owner
Joined: Dec 2000
Posts: 90,675
Likes: 304
From: SE NY
Cruise-In II Veteran
Not filmiliar with the AJ/FPR, but my Holley AFPR did not come with a O-ring.
Can't recall if there was an O-ring on top of the FPR diaphram.
Burning Brakes
Joined: Sep 2006
Posts: 1,142
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From: Spring Grove Illinois
My accel Did'nt have an O-ring either
Have you tried to block off or pinch closed the main fuel line (with key on)and watch if it leaks down slower..then block off return line and watch..If it slows down alot or stops check your fuel pump valve..Is there fuel in the Vacuum line of the FPR ??? Just some things to check,,Agent 86 Posted how to do this leak test a few weeks ago Do a search...Good Luck
Have you tried to block off or pinch closed the main fuel line (with key on)and watch if it leaks down slower..then block off return line and watch..If it slows down alot or stops check your fuel pump valve..Is there fuel in the Vacuum line of the FPR ??? Just some things to check,,Agent 86 Posted how to do this leak test a few weeks ago Do a search...Good Luck
Team Owner
Joined: Jan 2003
Posts: 20,322
Likes: 248
From: Summerland B.C. Canada
Have you checked FPR vac line for fuel ??
Start pinching some fuel lines.
http://members.shaw.ca/corvette86/Fu...mDiagnosis.pdf
Oh, and no O ring in my Holley or stock reg.
Start pinching some fuel lines.
http://members.shaw.ca/corvette86/Fu...mDiagnosis.pdf
Oh, and no O ring in my Holley or stock reg.
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