Need some fuel pump/fuel pressure tech help!!
Thread Starter
Instructor
Joined: Dec 2007
Posts: 189
Likes: 0
From: Loveland CO
Need some fuel pump/fuel pressure tech help!!
Hey guys, I'll try to keep this short and to the point, below is the situation and issues we're having:
-My buddies 2003 base C5 w/ a custom single turbo setup
The car just had 2 brand new dual 255 Walbro pumps installed by a local shop. Now it's runs and drives but cuts out with a moderate load on it.(it's got an OK base tune on it, but still has some bugs and we're not getting into boost as of yet) The weird thing that is happening now is that with the car running it reads around 55psi of fuel pressure at idle and when lightly revving in neutral. The second you turn the ignition off the fuel pressure drops to zero. We checked several times and it always drops immediately. If you just turn the ignition to "on" and don't fire the engine the pump(s) prime and build and hold pressure but as soon as you turn it to off it drops. Please correct me if I'm wrong, but shouldn't the fuel pressure hold and drop VERY slowly over a matter or hours??
If this makes any sense and you guys have a clue as to what may be happening please let me know. We may ofcourse take it back to the shop but we're hoping to get an idea what the issue is before anyone tears into it.
Thanks a ton.
-My buddies 2003 base C5 w/ a custom single turbo setup
The car just had 2 brand new dual 255 Walbro pumps installed by a local shop. Now it's runs and drives but cuts out with a moderate load on it.(it's got an OK base tune on it, but still has some bugs and we're not getting into boost as of yet) The weird thing that is happening now is that with the car running it reads around 55psi of fuel pressure at idle and when lightly revving in neutral. The second you turn the ignition off the fuel pressure drops to zero. We checked several times and it always drops immediately. If you just turn the ignition to "on" and don't fire the engine the pump(s) prime and build and hold pressure but as soon as you turn it to off it drops. Please correct me if I'm wrong, but shouldn't the fuel pressure hold and drop VERY slowly over a matter or hours??
If this makes any sense and you guys have a clue as to what may be happening please let me know. We may ofcourse take it back to the shop but we're hoping to get an idea what the issue is before anyone tears into it.
Thanks a ton.
Tech Contributor
Joined: Jan 2007
Posts: 19,470
Likes: 1,171
From: Dyer, IN
Hey guys, I'll try to keep this short and to the point, below is the situation and issues we're having:
-My buddies 2003 base C5 w/ a custom single turbo setup
The car just had 2 brand new dual 255 Walbro pumps installed by a local shop. Now it's runs and drives but cuts out with a moderate load on it.(it's got an OK base tune on it, but still has some bugs and we're not getting into boost as of yet) The weird thing that is happening now is that with the car running it reads around 55psi of fuel pressure at idle and when lightly revving in neutral. The second you turn the ignition off the fuel pressure drops to zero. We checked several times and it always drops immediately. If you just turn the ignition to "on" and don't fire the engine the pump(s) prime and build and hold pressure but as soon as you turn it to off it drops. Please correct me if I'm wrong, but shouldn't the fuel pressure hold and drop VERY slowly over a matter or hours??
If this makes any sense and you guys have a clue as to what may be happening please let me know. We may ofcourse take it back to the shop but we're hoping to get an idea what the issue is before anyone tears into it.
Thanks a ton.
-My buddies 2003 base C5 w/ a custom single turbo setup
The car just had 2 brand new dual 255 Walbro pumps installed by a local shop. Now it's runs and drives but cuts out with a moderate load on it.(it's got an OK base tune on it, but still has some bugs and we're not getting into boost as of yet) The weird thing that is happening now is that with the car running it reads around 55psi of fuel pressure at idle and when lightly revving in neutral. The second you turn the ignition off the fuel pressure drops to zero. We checked several times and it always drops immediately. If you just turn the ignition to "on" and don't fire the engine the pump(s) prime and build and hold pressure but as soon as you turn it to off it drops. Please correct me if I'm wrong, but shouldn't the fuel pressure hold and drop VERY slowly over a matter or hours??
If this makes any sense and you guys have a clue as to what may be happening please let me know. We may ofcourse take it back to the shop but we're hoping to get an idea what the issue is before anyone tears into it.
Thanks a ton.
Melting Slicks
Joined: Jul 2007
Posts: 2,939
Likes: 7
From: Simpsonville SC
St. Jude Donor '09-'10
I had the RSI dual fuel pump hanger installed in my car. It does ue two Walboro 255 pumps. I ran two -AN6 lines from the output of these pumps to each fuel rail. On the front of the fuel rails, I ran lines to a pressure regulator. The output of the regulator then runs back to the tank as the return line.
In my setup, as soon as I turn off the key, my pressure goes to zero.Tis is due to the regulator having a return line.
When I want to start my car, I turn the key to the ON position, and wait for the pumps to prime for 2 seconds, then I can start my engine.
In my setup, as soon as I turn off the key, my pressure goes to zero.Tis is due to the regulator having a return line.
When I want to start my car, I turn the key to the ON position, and wait for the pumps to prime for 2 seconds, then I can start my engine.
Tech Contributor
Joined: Jan 2007
Posts: 19,470
Likes: 1,171
From: Dyer, IN
I had the RSI dual fuel pump hanger installed in my car. It does ue two Walboro 255 pumps. I ran two -AN6 lines from the output of these pumps to each fuel rail. On the front of the fuel rails, I ran lines to a pressure regulator. The output of the regulator then runs back to the tank as the return line.
In my setup, as soon as I turn off the key, my pressure goes to zero.Tis is due to the regulator having a return line.
When I want to start my car, I turn the key to the ON position, and wait for the pumps to prime for 2 seconds, then I can start my engine.
In my setup, as soon as I turn off the key, my pressure goes to zero.Tis is due to the regulator having a return line.
When I want to start my car, I turn the key to the ON position, and wait for the pumps to prime for 2 seconds, then I can start my engine.
Tech Contributor
Joined: Jan 2007
Posts: 19,470
Likes: 1,171
From: Dyer, IN
I had the RSI dual fuel pump hanger installed in my car. It does ue two Walboro 255 pumps. I ran two -AN6 lines from the output of these pumps to each fuel rail. On the front of the fuel rails, I ran lines to a pressure regulator. The output of the regulator then runs back to the tank as the return line.
In my setup, as soon as I turn off the key, my pressure goes to zero.Tis is due to the regulator having a return line.
When I want to start my car, I turn the key to the ON position, and wait for the pumps to prime for 2 seconds, then I can start my engine.
In my setup, as soon as I turn off the key, my pressure goes to zero.Tis is due to the regulator having a return line.
When I want to start my car, I turn the key to the ON position, and wait for the pumps to prime for 2 seconds, then I can start my engine.
Corvette Stories
The Best of Corvette for Corvette Enthusiasts
Top 10 Most Expensive Corvettes Ever Sold on Bring A Trailer
Brett Foote
10 Things Every Corvette Owner Needs (2026 Edition)
Michael S. Palmer
8 Most "Only Corvette Owners Understand" Quirks and Problems
Pouria Savadkouei
10 Reasons the C6 Z06 is Still A Performance Benchmark After 20 Years
Joe Kucinski
How Much Horsepower Every Corvette Engine "LOST" in 1972
Joe Kucinski
Top 10 DOs and DON'Ts for Protecting Your Convertible Top!
Michael S. Palmer
Top 10 Most Explosive Corvettes Ever Made: Power-to-Weight Ratio Ranked!
Joe Kucinski
150 hp to 1,250 hp: Every Corvette Generation Compared by the Specs That Matter
Joe Kucinski
