Odd fuel pressure problem.
Thread Starter
Drifting
Joined: Aug 2007
Posts: 1,924
Likes: 6
Odd fuel pressure problem.
This one is really driving me crazy
My 81 has an electric fuel pump in the rear. When I first start the car, there is a solid 6 psi of pressure at the carb. Slowly, though within a 1/2 hour of running, the pressure drops eventually to near 0. It affects the running of the car, from nice to 'I can tell it's gasping for gas'
I changed the fuel pump (Holley Blue regulated) to a Holley Red and removed the regulator. But the same issue remains.
The hoses don't look decreped. So I'm struggling for answers. Is this normal for a Holley pump?
disclaimers:
yes, I know it should be on a mechanical pump, but the cam is missing in the timing chain cover and I don't have the time to tear down the front of the engine for the next 6 months (immenant house move)
yes, there's a kill switch
My 81 has an electric fuel pump in the rear. When I first start the car, there is a solid 6 psi of pressure at the carb. Slowly, though within a 1/2 hour of running, the pressure drops eventually to near 0. It affects the running of the car, from nice to 'I can tell it's gasping for gas'
I changed the fuel pump (Holley Blue regulated) to a Holley Red and removed the regulator. But the same issue remains.
The hoses don't look decreped. So I'm struggling for answers. Is this normal for a Holley pump?
disclaimers:
yes, I know it should be on a mechanical pump, but the cam is missing in the timing chain cover and I don't have the time to tear down the front of the engine for the next 6 months (immenant house move)
yes, there's a kill switch
Pro
Joined: Apr 2006
Posts: 625
Likes: 49
From: Southern California
Couple things:
1. Check to make sure the fuel tank vent is working as it should. I'm not sure what kind of smog stuff is on an 81, but try leaving the gas cap unlatched. Put a rag or something around the opeing, something that can vent. Then try to drive so that you don't slosh fuel too much, if you can, and see how she does. It sounds like you may just have a vent issue. Its worth a look.
2. Traditional Chevy's don't have a fuel pump cam behind the timing cover, that's why you never saw one. Its on the cam itself, so you have it there right now. If you want to switch to a mechanical fuel pump, all you need is the pump and its pushrod. Then sort out the fuel line as needed.
1. Check to make sure the fuel tank vent is working as it should. I'm not sure what kind of smog stuff is on an 81, but try leaving the gas cap unlatched. Put a rag or something around the opeing, something that can vent. Then try to drive so that you don't slosh fuel too much, if you can, and see how she does. It sounds like you may just have a vent issue. Its worth a look.
2. Traditional Chevy's don't have a fuel pump cam behind the timing cover, that's why you never saw one. Its on the cam itself, so you have it there right now. If you want to switch to a mechanical fuel pump, all you need is the pump and its pushrod. Then sort out the fuel line as needed.
Thread Starter
Drifting
Joined: Aug 2007
Posts: 1,924
Likes: 6
Couple things:
1. Check to make sure the fuel tank vent is working as it should. I'm not sure what kind of smog stuff is on an 81, but try leaving the gas cap unlatched. Put a rag or something around the opeing, something that can vent. Then try to drive so that you don't slosh fuel too much, if you can, and see how she does. It sounds like you may just have a vent issue. Its worth a look.
2. Traditional Chevy's don't have a fuel pump cam behind the timing cover, that's why you never saw one. Its on the cam itself, so you have it there right now. If you want to switch to a mechanical fuel pump, all you need is the pump and its pushrod. Then sort out the fuel line as needed.
1. Check to make sure the fuel tank vent is working as it should. I'm not sure what kind of smog stuff is on an 81, but try leaving the gas cap unlatched. Put a rag or something around the opeing, something that can vent. Then try to drive so that you don't slosh fuel too much, if you can, and see how she does. It sounds like you may just have a vent issue. Its worth a look.
2. Traditional Chevy's don't have a fuel pump cam behind the timing cover, that's why you never saw one. Its on the cam itself, so you have it there right now. If you want to switch to a mechanical fuel pump, all you need is the pump and its pushrod. Then sort out the fuel line as needed.
2. Must be from my mopar days I'm dragging this around with me. DOH! I'll be ordering up the mechanical pump and rod toot sweet.
I assume it's a filtering part? In the tank? On the pickup tube? Do I need it if there is a filter before the pump (which is right behind the Corvette nameplate at the rear.
Le Mans Master
Joined: Jan 2006
Posts: 9,192
Likes: 27
From: Boca Raton Florida
This thing is on the end of the pickup tube in the tank.
http://www.ecklers.com/product.asp?p...4&dept_id=1275
There is a rubber tube connecting the pickup tube to the frame rail fuel line, it may be collapsing inside. Good point 540 RAT made about the vent, drive it around until its failing and then open the fuel cap, if its related to the vent it should go to running fina again with the cap off.
http://www.ecklers.com/product.asp?p...4&dept_id=1275
There is a rubber tube connecting the pickup tube to the frame rail fuel line, it may be collapsing inside. Good point 540 RAT made about the vent, drive it around until its failing and then open the fuel cap, if its related to the vent it should go to running fina again with the cap off.
Thread Starter
Drifting
Joined: Aug 2007
Posts: 1,924
Likes: 6
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