Fuel In Vacuum Line
Thread Starter
Racer
Joined: Sep 2002
Posts: 420
Likes: 1
From: SAN DIEGO CA
Fuel In Vacuum Line
My 86 TPI vette has trouble starting when hot. I am going to do the fuel pressure test by pinching off the return line at the pump but I noticed something weird while removing a vacuum line to get to the schrader valve. What I noticed was fuel in the vacuum line. This is the vacuum line that actually hooks up to the plenum itself not the AFPR. On SR plenums there are two connections at the back of the SR to connect vacuum lines. The one on the far right (towards passenger side) had the fuel in it. I didnt notice any fuel on the hose that connects to the AFPR. Does this sound like a bad AFPR? If so, where should I buy the new one? I bought the last one from Lingenfelter about 4 years or so ago.
Burning Brakes
Joined: Nov 2005
Posts: 848
Likes: 1
From: 1992 LT1 6 speed Cayman Islands
Pull the line that goes to the FPR at the FPR and see if there is fuel in this line. If there is fuel in the line then you have a ruptured diaphram inside the FPR. You can usually replace these if that is the problem.
Jerris
Jerris
Instructor
Joined: Sep 2005
Posts: 145
Likes: 0
I have had a similar problem (among many others) with my '86 Vette. it is very possible that your FPR diaphragm has been compromised and fuel is getting sucked into your vacuum line from the pressure or the return side of the FPR.
In my case, it turned out to be a vacuum operated check valve that connects between the fuel vapor line to the gas tank and the fuel vapor canister. The leak in the diaphragm was ported to the inlet side, causing the vacuum system to actively suck fuel vapor from the gas tank instead of porting it to the fuel vapor canister. Crazy stuff.
If you want to read about more crazy troubleshooting adventures with my car, check out the epic post at http://forums.corvetteforum.com/show...24&forum_id=48. There's a ton of great information there.
In my case, it turned out to be a vacuum operated check valve that connects between the fuel vapor line to the gas tank and the fuel vapor canister. The leak in the diaphragm was ported to the inlet side, causing the vacuum system to actively suck fuel vapor from the gas tank instead of porting it to the fuel vapor canister. Crazy stuff.
If you want to read about more crazy troubleshooting adventures with my car, check out the epic post at http://forums.corvetteforum.com/show...24&forum_id=48. There's a ton of great information there.
Last edited by red86man; Jan 18, 2006 at 10:25 PM.
Thread Starter
Racer
Joined: Sep 2002
Posts: 420
Likes: 1
From: SAN DIEGO CA
fuel
I recently pulled off the entire front bumper assembly so that i could realign it. I pulled off the fuel canister and and all the hoses. Maybe when I ran the car without this stuff connected I messed it up. Or maybe I didnt hook up the lines right? Does anyone have a diagram of where the hoses connect in regards to the fuel canister located in the front left (drivers side) bumper area. I'm in the process of replacing the old hoses down there. 
Team Owner
Joined: Jan 2003
Posts: 20,335
Likes: 264
From: Summerland B.C. Canada
Thread Starter
Racer
Joined: Sep 2002
Posts: 420
Likes: 1
From: SAN DIEGO CA
fuel
I see a little dampness on the outside of the AFPR. I am assuming mine is leaking. I've noticed it for a few months now. Can you just replace the rubber gasket or should I just replace the whole thing with a new one? If replacing, where should I get the new one? Have you guys heard of any deals on decent AFPR?
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Drifting
Joined: May 2002
Posts: 1,509
Likes: 3
From: Hazel Park MI
Depending on whom you buy the AFPR from, you may or may not get a diaphram. I bought a TPIS unit, and had to use my stock diaphram, which promptly took a crap. I bought another one (diaphram) from corvette central. I would get the holley AFPR, as it comes with a diaphram and is comparable in price, and seems to be a reliable unit according to folks here on this forum. 
