Starving for fuel
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More Turbo
Joined: Apr 2009
Posts: 633
Likes: 4
From: Edmonton, Ab
Starving for fuel
My 79 has a 429, Holley manual fuel pump, Quick Fuel regulator.
I have a newer sending unit and new lines put in 2 months ago.
Truck starts fine, idles fine. I would start driving, then hear a little popping out of the exhaust, followed by the truck sputtering then stalling. Starts right back up.
I have a fuel pressure regulator under the hood. If I re start the truck, I have 2 PSI. If I let it idle for 10 minutes it goes back to 6, no higher. Start driving and it does it again. I have 2 online fuel filter which I replaced today, both were like new.
I tried adjusting the regulator and it made no difference.
Could my fuel pump be bad already? I have no leaks, checked all fittings.
I have a newer sending unit and new lines put in 2 months ago.
Truck starts fine, idles fine. I would start driving, then hear a little popping out of the exhaust, followed by the truck sputtering then stalling. Starts right back up.
I have a fuel pressure regulator under the hood. If I re start the truck, I have 2 PSI. If I let it idle for 10 minutes it goes back to 6, no higher. Start driving and it does it again. I have 2 online fuel filter which I replaced today, both were like new.
I tried adjusting the regulator and it made no difference.
Could my fuel pump be bad already? I have no leaks, checked all fittings.
Grumpy goat
Joined: May 2017
Posts: 3,058
Likes: 594
Sounds like your fuel tank is not vented. Fuel pump is literally pulling a vacuum on the tank until it overcomes the fuel pumps ability to pull fuel. Try all the things you normally do, except with fuel cap removed. If it runs fine, then you need to vent somehow. If you don't have a way to vent the tank, you can simply drill a tiny hole in your fuel cap.
Thread Starter
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More Turbo
Joined: Apr 2009
Posts: 633
Likes: 4
From: Edmonton, Ab
Fuel tank has a vent in the fill hose, as well as the small vent on top of tank. I also took the fuel cap off this morning just incase. No change.
I picked up a fuel pump tonight to try.
I picked up a fuel pump tonight to try.
Grumpy goat
Joined: May 2017
Posts: 3,058
Likes: 594
Yep, that'd be my next step too. It's probably the right move, but I have a bad habit of throwing parts at a problem before really digging into it. Oh, and the vent in the filler hose doesn't vent when the cap is on. It's there to vent displaced air while filling the tank. I hate tracking fuel flow issues more than I hate electrical gremlins.
Your fuel pressure gauge reads 2 psi when the problem occurs? So the issue is probably not downstream of the fuel pump. So in order from front to rear...Clogged filter, bad pump, line blockage, clogged pickup or sock, tank vent.
Your fuel pressure gauge reads 2 psi when the problem occurs? So the issue is probably not downstream of the fuel pump. So in order from front to rear...Clogged filter, bad pump, line blockage, clogged pickup or sock, tank vent.
Cargo Master
Joined: Dec 2008
Posts: 3,213
Likes: 321
From: SW PA
If the pressure won’t change either up or down with regulator adjustments, I would look there first IMO.
if it will go down but not up, I would look at pump.
Easiet and sure fire way to be sure is check pressure with regulator removed from system.
if it will go down but not up, I would look at pump.
Easiet and sure fire way to be sure is check pressure with regulator removed from system.
FTE Legend
Joined: Nov 2015
Posts: 30,912
Likes: 4,123
From: Angier, NC
The big question why the regulator?
I have not known a manual pump to be to high a psi to need a regulator.
Remove that regulator and see what happens.
Next big question why 2 filters and where are they installed, before or after the pump?
There is nothing wrong with the factory fuel system supply setup so what go messing with it?
Tank that is vented, sock on the in tank pick up, little rubber hose to metal line along the frame, little rubber hose from metal line to pump on motor, metal line going to carb with a filter between pump & carb that may or may not use rubber hose.
BTW have you replaced ALL the rubber hose with new hose? They can look good on the out side and fall apart and plug on the inside or have a pinhole that will suck air but not leak fuel out.
You said you removed the gas cap and drove the truck and it had the same issue?
What carb you running?
Dave ----
I have not known a manual pump to be to high a psi to need a regulator.
Remove that regulator and see what happens.
Next big question why 2 filters and where are they installed, before or after the pump?
There is nothing wrong with the factory fuel system supply setup so what go messing with it?
Tank that is vented, sock on the in tank pick up, little rubber hose to metal line along the frame, little rubber hose from metal line to pump on motor, metal line going to carb with a filter between pump & carb that may or may not use rubber hose.
BTW have you replaced ALL the rubber hose with new hose? They can look good on the out side and fall apart and plug on the inside or have a pinhole that will suck air but not leak fuel out.
You said you removed the gas cap and drove the truck and it had the same issue?
What carb you running?
Dave ----
Thread Starter
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More Turbo
Joined: Apr 2009
Posts: 633
Likes: 4
From: Edmonton, Ab
The big question why the regulator?
I have not known a manual pump to be to high a psi to need a regulator.
Remove that regulator and see what happens.
Next big question why 2 filters and where are they installed, before or after the pump?
There is nothing wrong with the factory fuel system supply setup so what go messing with it?
Tank that is vented, sock on the in tank pick up, little rubber hose to metal line along the frame, little rubber hose from metal line to pump on motor, metal line going to carb with a filter between pump & carb that may or may not use rubber hose.
BTW have you replaced ALL the rubber hose with new hose? They can look good on the out side and fall apart and plug on the inside or have a pinhole that will suck air but not leak fuel out.
You said you removed the gas cap and drove the truck and it had the same issue?
What carb you running?
Dave ----
I have not known a manual pump to be to high a psi to need a regulator.
Remove that regulator and see what happens.
Next big question why 2 filters and where are they installed, before or after the pump?
There is nothing wrong with the factory fuel system supply setup so what go messing with it?
Tank that is vented, sock on the in tank pick up, little rubber hose to metal line along the frame, little rubber hose from metal line to pump on motor, metal line going to carb with a filter between pump & carb that may or may not use rubber hose.
BTW have you replaced ALL the rubber hose with new hose? They can look good on the out side and fall apart and plug on the inside or have a pinhole that will suck air but not leak fuel out.
You said you removed the gas cap and drove the truck and it had the same issue?
What carb you running?
Dave ----
There is a filter before and after the pump, I run it like this on all my vehicles. They are the earls with bronze filters. All new fuel lines run from front to back. Quality stuff.
I built the truck from scratch, there was nothing stock to go from.
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Fleet Owner
Joined: Jan 2004
Posts: 26,007
Likes: 575
From: Brentwood,CA
So if you are using the quick fuel regulator what are you doing with the return port? I guess I don't understand why its installed? The fuel pump is 6.5 to 8psi regulated internally.
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FTE Legend
Joined: Nov 2015
Posts: 30,912
Likes: 4,123
From: Angier, NC
I rum that pump on my drag car with out issues.
Now if the 110 GPH p u mp is the red one and think g it is if gas hog is right on the output psi they don't use a regulator.
Also Holley carbs are pretty good on being able to control a little higher psi than the eldebrock carbs.
I would remove that regulator and run straight from pump to carb and see what happens.
Dave - - - -
Mountain Pass
Joined: Sep 2004
Posts: 127
Likes: 29
From: s/e iowa
I had the same symptoms. Check your pre pump filter inlet, then the pump inlet. Ethanol gas deteriorated my fuel tank filler hose and plugged the fuel pump inlet (gel like substance). My pump was new so it was the last thing i looked at.
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