New Mechanical Fuel pumps
Thread Starter
Burning Brakes
Joined: Sep 2019
Posts: 923
Likes: 155
From: North Port, FL
New Mechanical Fuel pumps
I recently had a problem with fuel delivery with a Quadrijet that I had Lars rebuild for me. After doing some checking I was told that some newer mechanical pumps come thru with too much pressure.
Testing mine, it had been putting out 11lbs of fuel pressure. I was also told that the fix for this is to add gaskets between the block and the pump to lower the pressure. Has anyone else ever come across
this problem? This is a new pump I got from Summit, not rebuilt.
Thanks
Testing mine, it had been putting out 11lbs of fuel pressure. I was also told that the fix for this is to add gaskets between the block and the pump to lower the pressure. Has anyone else ever come across
this problem? This is a new pump I got from Summit, not rebuilt.
Thanks
Thread Starter
Burning Brakes
Joined: Sep 2019
Posts: 923
Likes: 155
From: North Port, FL
Its been a while, OEM style I got I think from Summit. Ive bypassed it for the time being and I'm just using a Holley elec pump. Gauge says 6lbs.now. I suppose I could use the old mech
pump. I got all new stuff when I dressed the new engine. BTW, the guage read 11lbs before I put the elec pump on.
pump. I got all new stuff when I dressed the new engine. BTW, the guage read 11lbs before I put the elec pump on.
Race Director
Joined: Mar 2017
Posts: 11,944
Likes: 4,506
From: Virginia
Its been a while, OEM style I got I think from Summit. Ive bypassed it for the time being and I'm just using a Holley elec pump. Gauge says 6lbs.now. I suppose I could use the old mech
pump. I got all new stuff when I dressed the new engine. BTW, the guage read 11lbs before I put the elec pump on.
pump. I got all new stuff when I dressed the new engine. BTW, the guage read 11lbs before I put the elec pump on.
Race Director
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From: Sunshine Coast, Queensland, Australia
2025 C3 of the Year Finalist - Modified
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Not so certain he has it solved. Electric pump? In the tank? Or inline outside the tank?
intank, reliable.
Inline outside the tank, definitely NOT .
intank, reliable.
Inline outside the tank, definitely NOT .
Thread Starter
Burning Brakes
Joined: Sep 2019
Posts: 923
Likes: 155
From: North Port, FL
I'd still like to know if anyone else has had the over pressure problem. Or is my problem is unusual. Also if they solved it by adding gaskets.
Thanks
Pro
Joined: Nov 2023
Posts: 701
Likes: 335
From: Aubrey TX
I had the same problem. Troubleshooting back and forth with Lars, we determined my stock mech pump, replace by PO was making just under 10lbs pressure and was too high but not by much. My first fix was to find an OEM GM pump and try that but that was worse and made just under 11 lbs. So I cut the fuel line to the carb and inserted a regulator and hat solved my fuel dribble problem. This was all last march / april (2024) and its been all good since then. I agree its irritating to have to fix a problem that should not have existed in the first place... But here we are.
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Race Director
Joined: Mar 2017
Posts: 11,944
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From: Virginia
I had the same problem. Troubleshooting back and forth with Lars, we determined my stock mech pump, replace by PO was making just under 10lbs pressure and was too high but not by much. My first fix was to find an OEM GM pump and try that but that was worse and made just under 11 lbs. So I cut the fuel line to the carb and inserted a regulator and hat solved my fuel dribble problem. This was all last march / april (2024) and its been all good since then. I agree its irritating to have to fix a problem that should not have existed in the first place... But here we are.
Pro
Joined: Aug 2000
Posts: 610
Likes: 168
From: Vancouver B.C.
Had same problem with a new Carter fuel pump that was described as their classic car series with correct fuel pressure. I did an engine refresh and decided to install a new fuel pump. Meanwhile, also had my QJet professionally rebuilt. Had nozzle drip at idle after all installed upon start up. Checked fuel pressure. Had 9.5 lbs pressure. Too much. Ending up using an inline regulator (smaller Mr. gasket style p/n 9710) that I was not happy with having to use. I wanted only a fuel line from pump to carb. Of course, I discarded my perfectly good old fuel pump that had correct pressure. Carter QC is not good.
Thread Starter
Burning Brakes
Joined: Sep 2019
Posts: 923
Likes: 155
From: North Port, FL
Had same problem with a new Carter fuel pump that was described as their classic car series with correct fuel pressure. I did an engine refresh and decided to install a new fuel pump. Meanwhile, also had my QJet professionally rebuilt. Had nozzle drip at idle after all installed upon start up. Checked fuel pressure. Had 9.5 lbs pressure. Too much. Ending up using an inline regulator (smaller Mr. gasket style p/n 9710) that I was not happy with having to use. I wanted only a fuel line from pump to carb. Of course, I discarded my perfectly good old fuel pump that had correct pressure. Carter QC is not good.
Did you just used braided gas line?.
Thanks for the info.
Burning Brakes
Joined: Oct 2001
Posts: 925
Likes: 200
From: TX
Jarhead
(Haha. I have lots of jarhead friends with whom I shoot.)
If you want to gamble about
$40 you might try this pump I got at NAPA, part number B-0172-P. It's been on for over six years and must be the right pressure as it runs my Lars built Quadrajet flawlessly. As I recall, the box said made in South Korea with Carter engineering. But it sure works. Engine is a 1969 350/300.
VS
(Haha. I have lots of jarhead friends with whom I shoot.)
If you want to gamble about
$40 you might try this pump I got at NAPA, part number B-0172-P. It's been on for over six years and must be the right pressure as it runs my Lars built Quadrajet flawlessly. As I recall, the box said made in South Korea with Carter engineering. But it sure works. Engine is a 1969 350/300.
VS
Pro
Joined: Aug 2000
Posts: 610
Likes: 168
From: Vancouver B.C.
Although I threw out my old pump, I still had the old factory steel
fuel line that was cut prior for a filter. I reused it, and used rubber hose and hose clamps. I prefer a solid line, been a bit lazy and left it as is, my thinking and hope is one day I can get a calibrated pump that is factory rated.
fuel line that was cut prior for a filter. I reused it, and used rubber hose and hose clamps. I prefer a solid line, been a bit lazy and left it as is, my thinking and hope is one day I can get a calibrated pump that is factory rated.
Thread Starter
Burning Brakes
Joined: Sep 2019
Posts: 923
Likes: 155
From: North Port, FL
Jarhead
(Haha. I have lots of jarhead friends with whom I shoot.)
If you want to gamble about
$40 you might try this pump I got at NAPA, part number B-0172-P. It's been on for over six years and must be the right pressure as it runs my Lars built Quadrajet flawlessly. As I recall, the box said made in South Korea with Carter engineering. But it sure works. Engine is a 1969 350/300.
VS
(Haha. I have lots of jarhead friends with whom I shoot.)
If you want to gamble about
$40 you might try this pump I got at NAPA, part number B-0172-P. It's been on for over six years and must be the right pressure as it runs my Lars built Quadrajet flawlessly. As I recall, the box said made in South Korea with Carter engineering. But it sure works. Engine is a 1969 350/300.
VS
Tell your Devil Dog buddies I said Semper Fi. You ever come my way I'll take you to a 1000yd range near by. Bring lots of ammo.
Le Mans Master
Joined: May 2007
Posts: 5,024
Likes: 1,120
From: North tonawanda NY
Right now all I have is the Holley elec pump, outside of the tank. That is suppose to be my back up pump. I guess I'll have to order another mech pump.
I'd still like to know if anyone else has had the over pressure problem. Or is my problem is unusual. Also if they solved it by adding gaskets.
Thanks
I'd still like to know if anyone else has had the over pressure problem. Or is my problem is unusual. Also if they solved it by adding gaskets.
Thanks
BTW the ac replacement pumps are all over the place in quality and made all over too.. I believe carter contracts them out to be made now.
Thread Starter
Burning Brakes
Joined: Sep 2019
Posts: 923
Likes: 155
From: North Port, FL
As mentioned the right way to fix this long term is to just add the regulator. I have had 4 different "oem" carter type replacement pumps on my car and the fuel pressures do vary quite a bit. the best most reliable setup is to add a regulator and adjust it for consistency.
BTW the ac replacement pumps are all over the place in quality and made all over too.. I believe carter contracts them out to be made now.
BTW the ac replacement pumps are all over the place in quality and made all over too.. I believe carter contracts them out to be made now.
Melting Slicks
Joined: Aug 2011
Posts: 3,124
Likes: 259
Right now all I have is the Holley elec pump, outside of the tank. That is suppose to be my back up pump. I guess I'll have to order another mech pump.
I'd still like to know if anyone else has had the over pressure problem. Or is my problem is unusual. Also if they solved it by adding gaskets.
Thanks
I'd still like to know if anyone else has had the over pressure problem. Or is my problem is unusual. Also if they solved it by adding gaskets.
Thanks
Thread Starter
Burning Brakes
Joined: Sep 2019
Posts: 923
Likes: 155
From: North Port, FL
Melting Slicks
Joined: Aug 2011
Posts: 3,124
Likes: 259
Mechanical pumps USED TO last forever - I used to just carry a spare pump with identical connections etc.
I can't see how "richarding" around with extra gaskets would reduce pressure - I believe it's the spring inside that determines the output pressure.
I run a Holley BLUE competition (15 psi) pump ONLY on my street driven '59 with their regulator up at the carb.
I have a pressure gauge on both sides of the regulator (in & out) - so I know whats going on
I get about 15 years out of the Holley pump before the seal starts to weep/leak - you get lots of warning - I have never had one flat out quit - just a very slight leak
I used to replace the seal - back when it was easy to buy the seal from a bearing supply house - I made a little puller jig to pull the pressed in vane race to disassemble the pump.
My biggest priority is to mount the pump away from the exhaust / heat and somewhere where it might get some cooling air flow.
The Holley RED (street) pump puts out about 5 psi and no regulator required (usually).
I would JUST go with a Holley RED pump and forego "richarding" around with a regulator and mechanical pumps
Last edited by QIK59; Dec 30, 2024 at 08:27 PM.
Thread Starter
Burning Brakes
Joined: Sep 2019
Posts: 923
Likes: 155
From: North Port, FL
Never heard of that before (two pumps) unless the electric pump was parallel to the mechanical pump - didn't think you could suck fuel through most electric pumps
Mechanical pumps USED TO last forever - I used to just carry a spare pump with identical connections etc.
I can't see how "richarding" around with extra gaskets would reduce pressure - I believe it's the spring inside that determines the output pressure.
I run a Holley BLUE competition (15 psi) pump ONLY on my '59 with their regulator up at the carb.
I have a pressure gauge on both sides of the regulator (in & out) - so I know whats going on
I get about 15 years out of the Holley pump before the seal starts to weep/leak - you get lots of warning - I have never had one flat out quit - just a very slight leak
I used to replace the seal - back when it was easy to buy the seal from a bearing supply house - I made a little puller jig to pull the pressed in vane race to disassemble the pump.
My biggest priority is to mount the pump away from the exhaust / heat and somewhere where it might get some cooling air flow.
The Holley RED (street) pump puts out about 5 psi and no regulator required (usually).
I would JUST go with a Holley RED pump and forego "richarding" around with a regulator and mechanical pumps
Mechanical pumps USED TO last forever - I used to just carry a spare pump with identical connections etc.
I can't see how "richarding" around with extra gaskets would reduce pressure - I believe it's the spring inside that determines the output pressure.
I run a Holley BLUE competition (15 psi) pump ONLY on my '59 with their regulator up at the carb.
I have a pressure gauge on both sides of the regulator (in & out) - so I know whats going on
I get about 15 years out of the Holley pump before the seal starts to weep/leak - you get lots of warning - I have never had one flat out quit - just a very slight leak
I used to replace the seal - back when it was easy to buy the seal from a bearing supply house - I made a little puller jig to pull the pressed in vane race to disassemble the pump.
My biggest priority is to mount the pump away from the exhaust / heat and somewhere where it might get some cooling air flow.
The Holley RED (street) pump puts out about 5 psi and no regulator required (usually).
I would JUST go with a Holley RED pump and forego "richarding" around with a regulator and mechanical pumps
my problems I disconnected it and now Im just running the elec one, but I'm gonna put a regulator after the mech pump and use that as my primary. Its a shame something as simple as a fuel pump cant be built right anymore.
All because someone wants to make a couple bucks more I guess.