Fuel pressure Loss
Thread Starter
Intermediate
Joined: Sep 2005
Posts: 42
Likes: 0
From: ny ny
Fuel pressure Loss
HiHi I am new to the forum and I’m not sure if this is the proper place for this question if not please let me know and I will move my post.
I have a 1977 Corvette with a 468 Big Block Chevy. I have an Edlebrock 800cfm AVS Carburetor, Edlebrock Air Gap intake manifold, and a Holly Electric Black series pump that is rated at 140 gph.
I am having problems with my fuel pressure. The problem that I am experiencing is fuel pressure loss when the car is under load or parked. I experience this problem When I am driving the car 40 to 50 mph the fuel pressure will drop from 6 ½ to 3 psi. When I stop the pressure goes back up to normal. When I have the car in park and just rev the gas I see the fuel pressure decline slowly.
The Edelbrock components are all new. I have tried replacing the fuel pump and installed a relay, I replaced the stock lines in the car with -8 stainless steel lines and areoquip fittings, I replaced the regulator with a Barry Grant 2 port regulator, and I replaced both fuel filters.
I have never experienced this problem before and I don’t know what else to try if anyone has any suggestions I would appreciate it.
I have a 1977 Corvette with a 468 Big Block Chevy. I have an Edlebrock 800cfm AVS Carburetor, Edlebrock Air Gap intake manifold, and a Holly Electric Black series pump that is rated at 140 gph.
I am having problems with my fuel pressure. The problem that I am experiencing is fuel pressure loss when the car is under load or parked. I experience this problem When I am driving the car 40 to 50 mph the fuel pressure will drop from 6 ½ to 3 psi. When I stop the pressure goes back up to normal. When I have the car in park and just rev the gas I see the fuel pressure decline slowly.
The Edelbrock components are all new. I have tried replacing the fuel pump and installed a relay, I replaced the stock lines in the car with -8 stainless steel lines and areoquip fittings, I replaced the regulator with a Barry Grant 2 port regulator, and I replaced both fuel filters.
I have never experienced this problem before and I don’t know what else to try if anyone has any suggestions I would appreciate it.
Racer
Joined: Jan 2004
Posts: 273
Likes: 0
Pressure Guage
I had a similar experience after swapping in my new motor. I spent all kinds of time and money swapping out fuel system components to explain the pressure drop to discover the problem was a result of the new liquid filled fuel pressure guage I mounted under the hood. Turns out there was never a problem to begin with as when the fluid in the guage heated up the pressure reading would drop. I was anything but impressed, turns out all the fluid filled guages do that and are only accurate on a cold start for the first minute. Expensive lesson for sure.
-Andre
-Andre
Drifting
Joined: Jul 2003
Posts: 1,253
Likes: 1
From: East China MI
Are you experiencing any performance problems?
Any power loss while cruising or accelerating?
If not, I'm with AndreG.
What kind of guage is it? Where is it mounted?
Check the ground on the guage (if remote), the fuel pump and the chassis.
Do you have electric fans with a stock alternator?
Any power loss while cruising or accelerating?
If not, I'm with AndreG.
What kind of guage is it? Where is it mounted?
Check the ground on the guage (if remote), the fuel pump and the chassis.
Do you have electric fans with a stock alternator?
Thread Starter
Intermediate
Joined: Sep 2005
Posts: 42
Likes: 0
From: ny ny
I do not have a liquid filled gauge. I have an auto meter mechanical gauge. Its tapped into the fuel line between the carb and regulator. It is mounted outside the car. i also have a gauge that is tapped right into the regulator and when i rev the motor the both have the same problem the pressure slowly declines. I have electric fans but i have a 110 amp altenator. i have a relay wired into my fuel pump so i dont think its a voltage probelm. I think some gasoline and matches would help me fix this for good 
Thanks for you're suggestions
Thanks for you're suggestions
Race Director
Joined: Jul 2001
Posts: 15,892
Likes: 42
Instead of gasoline and matches, trying putting some black electrical tape over the face of the gauge. Now drive the car as hard as you can. Does the problem still exist? No? Now you can get rid of the gauge completely and enjoy the car instead of worrying what's on a gauge. 
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Drifting
Joined: Jul 2003
Posts: 1,253
Likes: 1
From: East China MI
Originally Posted by thomascalandrino
the wires are grounded to the frame of the car by a bolt. do you think that could be a problem?
Do you have any performance issues?
Priority one is to determine if you have a fuel pressure problem or just a faulty guage. If the car runs fine in all modes, it's probably the guage.
Last edited by jpatrick636; Sep 28, 2005 at 06:46 PM.
Thread Starter
Intermediate
Joined: Sep 2005
Posts: 42
Likes: 0
From: ny ny
i dont think its the gauge because i have 2 pressure gauges and they both do the same thing. the ground is something i should look at becasue where it is grounded is a little rusty. do you think i should run the ground to the negative battey post?
Drifting
Joined: Jul 2003
Posts: 1,253
Likes: 1
From: East China MI
Originally Posted by thomascalandrino
i dont think its the gauge because i have 2 pressure gauges and they both do the same thing. the ground is something i should look at becasue where it is grounded is a little rusty. do you think i should run the ground to the negative battey post?
Thread Starter
Intermediate
Joined: Sep 2005
Posts: 42
Likes: 0
From: ny ny
Thanks for all you're help and suggestions guys. The problem is gone! Now that the weather here seems to be getting cooler I'm not experiencing the problem anymore. I guess it was vapor lock or someting 
. Which I can't see becasue I ran a new fuel line and made sure that it was not neat anything hot. Oh well at least it's gone for now.
I'm going to start doing my interior over. Would anyone happen to know of any good "how to" articles or something that would give me step by step instructions so I could get some idea on what I will be getting myself into. I decided to use interior dye (black) on certain things. Has anyone had any experience using interior dye? Does it look ok? I'm not looking for show quality just something to look decent.
Thanks
. Which I can't see becasue I ran a new fuel line and made sure that it was not neat anything hot. Oh well at least it's gone for now. I'm going to start doing my interior over. Would anyone happen to know of any good "how to" articles or something that would give me step by step instructions so I could get some idea on what I will be getting myself into. I decided to use interior dye (black) on certain things. Has anyone had any experience using interior dye? Does it look ok? I'm not looking for show quality just something to look decent.
Thanks
Burning Brakes
Joined: Apr 2004
Posts: 847
Likes: 0
From: Des Allemands LA
A quick note on dye. Do as many parts at the same time and same conditions with the same dye. Heat, humidity, how fast it dries will all contribute to the final shade it dries to.
ltlevil
ltlevil
