Register or Log In To remove these advertisements. |
|
|
|
Thread Tools | Display Modes |
10-31-2024, 08:42 PM | #1 |
New Member
Join Date: Mar 2024
Location: Bend, Oregon
Posts: 10
|
Sourcing 5-6 psi fuel pump help
Fuel pump went out on my '72 C20 350 with the stock quadrajet. The one that was on it was a AC Delco mechanical pump with a 3/8 outlet fitting and a return line with the elongated pump body. Took a while but I found this one from summit:
https://www.summitracing.com/parts/CRT-M6101 Installed and the carb is flooding, rebuilt the carb, adjusted float, still floods. Looked on carter's website and says the psi min is 7.5 and max 9, not the 6 summit states. ANYWAY.....anyone have any advice on finding one with lower pressure rating? From what I can tell quadrajet likes about 5 or 6psi. I'd prefer not to have to add a pressure regulator inline if I can avoid it. |
10-31-2024, 09:46 PM | #2 |
Senior Member
Join Date: May 2004
Location: Queen Creek, AZ
Posts: 1,010
|
Re: Sourcing 5-6 psi fuel pump help
I haven't heard about quadrajets being sensitive to pressure....Edelbrocks I hear alot of....one of the cures they use, if they dont want to use a separate fuel regulator, is they use an Edelbrock fuel pump...they pump at a lower psi....
|
10-31-2024, 09:59 PM | #3 |
Senior Member
Join Date: Jun 2022
Location: San Ramon,CA
Posts: 593
|
Re: Sourcing 5-6 psi fuel pump help
Is there fuel flowing back to the tank through the return?
__________________
1970 C10 Custom longbed 350/350 |
10-31-2024, 11:43 PM | #4 |
Registered User
Join Date: Apr 2014
Location: California
Posts: 975
|
Re: Sourcing 5-6 psi fuel pump help
I don't have particularly good news for you, but this issue is not anything new and is all over the internet.
The short of it is that the fix is to start running a pressure regulator. I run a stock Holley 1-bl carb on my old ford truck for 10 years with no regulator--thousands of miles between 2011 and 2021. Pump installed in 2013 or so went bad and replaced with a new one, and for heavens sake I couldn't get the bowl to stop overflowing. I paid $50 at autozone and got a simple regulator. Generally speaking it fixed my issue. The talk on the internet is that the pressure regulation of most new pumps is very loose, with most pumps putting out 8-9, and some youtube people saying they've seen 11-15 from a stock mechanical pump meant for an application that calls for 3-5 psi. Not ideal.... Good luck. |
11-01-2024, 04:08 PM | #5 |
Registered User
Join Date: Jul 2008
Location: Eastern Oregon
Posts: 2,392
|
Re: Sourcing 5-6 psi fuel pump help
I had the DualJet rebuilt for my 71 C/20 307. It would not run properly until I installed a fuel regulator. I had an inexpensive Mr Gasket on my shelf, installed it and set it for five lbs. engine runs like a sewing machine now.
__________________
71 C-20 07 Magnum RT AWD |
11-02-2024, 06:57 AM | #6 | |
All stock and staying that way
Join Date: Jul 2003
Location: Elkland, PA
Posts: 1,831
|
Re: Sourcing 5-6 psi fuel pump help
Quote:
__________________
1970 K/5 Blazer CST 4WD, Medium Bronze, 93k ACT. miles, 350, 4 speed, rear positraction, 16.5" x 8.25" HD wheel option, tilt, tach, vacuum, AM/FM, manual throttle...Dad ordered and purchased new 4/70. Currently frame off restoration finally getting close to completion.. 1972 Cheyenne Super 20 2WD, DK Blue/White, 90K ACT. miles, 402, TH400, 4.10 open, tilt, tach, vacuum, A/C, AM/FM, manual throttle.. A mostly original paint never rusted Texas survivor... 2017 Sierra 1500 SLT 4WD, Black, 45k miles, 5.3, 6L80E, 3.42 LS, 20" polished wheels, everything but moonroof and 6.2... 2019 Canyon SLT 4WD, White, 62k miles, 3.6, 8L45, 3.23 LS, 18" wheels |
|
11-02-2024, 10:48 AM | #7 |
Registered User
Join Date: Aug 2015
Location: kokomo,indiana
Posts: 336
|
Re: Sourcing 5-6 psi fuel pump help
Had a Rochester on mine from the Start, kept having issues with it, Carb not fuel pressure, pressure with Stock Fuel Pump was always 8 to 9
Bought an Edelbrock and hooked up Pressure Regulator Not had an issue since Besides, the Regulator looks Custom. lol But i already bought an Edelbrock Fuel pump 6 PSI max, going to change it out this Winter, probably still run the regulator
__________________
A Little Better Every Day Cancer Survivor, most dont know what they have until its gone, appreciate everything Last edited by twoskies; 11-02-2024 at 10:54 AM. Reason: more |
11-08-2024, 07:25 AM | #8 |
New Member
Join Date: Mar 2024
Location: Bend, Oregon
Posts: 10
|
Re: Sourcing 5-6 psi fuel pump help
Appreciate all the knowledge and advice. Threw the mr. gasket dial regulator on just for simplicity's sake before committing to ordering a more quality option. Still having the flooding issue with the carb. I think the plan at this point is to swap the float in the carb out, switch the mechanical fuel pump with the return out for one without a return, and then install a regulator downstream with a return line.
When it comes to mechanical fuel pumps why are some flatter and others the cylinders are elongated like a soup can? |
11-08-2024, 08:34 AM | #9 |
All stock and staying that way
Join Date: Jul 2003
Location: Elkland, PA
Posts: 1,831
|
Re: Sourcing 5-6 psi fuel pump help
Seeing tons of utter failures right out of the box with recently produced pumps, I'd rather chance a NOS pump at this point!
Here is the correct one for your application: 1972 series 20 350 with Turbo Hydramatic: 6470569 or 40867
__________________
1970 K/5 Blazer CST 4WD, Medium Bronze, 93k ACT. miles, 350, 4 speed, rear positraction, 16.5" x 8.25" HD wheel option, tilt, tach, vacuum, AM/FM, manual throttle...Dad ordered and purchased new 4/70. Currently frame off restoration finally getting close to completion.. 1972 Cheyenne Super 20 2WD, DK Blue/White, 90K ACT. miles, 402, TH400, 4.10 open, tilt, tach, vacuum, A/C, AM/FM, manual throttle.. A mostly original paint never rusted Texas survivor... 2017 Sierra 1500 SLT 4WD, Black, 45k miles, 5.3, 6L80E, 3.42 LS, 20" polished wheels, everything but moonroof and 6.2... 2019 Canyon SLT 4WD, White, 62k miles, 3.6, 8L45, 3.23 LS, 18" wheels |
11-08-2024, 08:57 AM | #10 |
Senior Member
Join Date: Jun 2002
Location: Murray, Kentucky
Posts: 3,475
|
Re: Sourcing 5-6 psi fuel pump help
Keep an eye on the Mr. Gasket dial type regulators. Had one on my blazer and the gasket failed after a year or so. Very exciting episode.
It was in 2018 so maybe they have fixed the problem??? Good luck, Rg
__________________
Roger '68 Short step - https://67-72chevytrucks.com/vboard/...d.php?t=849675 '69 ('70?) 2wd Blazer '70 GMC Jimmy 2wd '73 Firebird - https://67-72chevytrucks.com/vboard/...d.php?t=853203 |
11-08-2024, 11:26 AM | #11 |
New Member
Join Date: Mar 2024
Location: Bend, Oregon
Posts: 10
|
Re: Sourcing 5-6 psi fuel pump help
Would rather not reroute the lines in place, any idea what the model number for the outlet orientation that would be similar to the Carter one I got from summit would be?
|
11-08-2024, 12:01 PM | #12 |
All stock and staying that way
Join Date: Jul 2003
Location: Elkland, PA
Posts: 1,831
|
Re: Sourcing 5-6 psi fuel pump help
Looks similar to me!
__________________
1970 K/5 Blazer CST 4WD, Medium Bronze, 93k ACT. miles, 350, 4 speed, rear positraction, 16.5" x 8.25" HD wheel option, tilt, tach, vacuum, AM/FM, manual throttle...Dad ordered and purchased new 4/70. Currently frame off restoration finally getting close to completion.. 1972 Cheyenne Super 20 2WD, DK Blue/White, 90K ACT. miles, 402, TH400, 4.10 open, tilt, tach, vacuum, A/C, AM/FM, manual throttle.. A mostly original paint never rusted Texas survivor... 2017 Sierra 1500 SLT 4WD, Black, 45k miles, 5.3, 6L80E, 3.42 LS, 20" polished wheels, everything but moonroof and 6.2... 2019 Canyon SLT 4WD, White, 62k miles, 3.6, 8L45, 3.23 LS, 18" wheels |
11-08-2024, 01:23 PM | #13 |
New Member
Join Date: Mar 2024
Location: Bend, Oregon
Posts: 10
|
Re: Sourcing 5-6 psi fuel pump help
One I pulled off in on the left and the one on the right is the 40867. Hard to see in pics but on the 40867 the inlet/return are pointed straight at the radiator/fan whereas the old one, they point towards the fender.
|
11-08-2024, 01:35 PM | #14 |
Registered User
Join Date: Jul 2008
Location: Eastern Oregon
Posts: 2,392
|
Re: Sourcing 5-6 psi fuel pump help
I bought a pump from Napa for my 307. The threads for the input line were buggered up so bad that the inlet line would not engage into the pump. Returned it and found a nos Delco pump. Still working fine years later.
__________________
71 C-20 07 Magnum RT AWD |
11-10-2024, 08:56 PM | #15 |
Registered User
Join Date: Jun 2019
Location: Chehalis, WA
Posts: 73
|
Re: Sourcing 5-6 psi fuel pump help
At 40 GPH and even 9 PSI, I can't see how that's causing flooding. You don't need a fuel pressure regulator at that output.
What I typically find is that it's not the PSI - it's the GPH; "muscle car" pumps tend to put out 100+ GPH and that's just too much for stock carb to deadhead at. But that's not what's happening here. I would check the needle and seat again to be sure there's not a piece of gunk there from when you changed the pump. I'm confident the problem isn't flow or pressure overwhelming the seat - it's that the seat isn't closing. I've also seen a ton more failures in stock pumps out of the box any more; I only run Holley mechanical pumps any more for carbs. Rebuildable, too - and you can clock the outlets. |
11-13-2024, 05:49 PM | #16 |
Senior Member
Join Date: Jul 2000
Location: North Texas
Posts: 3,597
|
Re: Sourcing 5-6 psi fuel pump help
Rock Auto also shows these:
Carter M6624 -- 2 line Carter M6215 -- 3 line; long pump housing They also list two more by Delphi, which used to mean good quality.
__________________
Mike 1969 C10 LWB -- owned for 35 years. 350/TH350, 3.08 posi, 1st Gen Vintage Air, recent AAW wiring harness, 5-lug conversion, 1985 spindles and brakes. 1982 C10 SWB -- sold 1981 C10 Silverado LWB -- sold, but wish I still had it! 1969 C10 (not the current one) that I bought in the early 1980s. Paid $1200; sold for $1500 a few years later. Just a hint at the appreciation that was coming. Retired as a factory automation products salesman. Worked part-time over the years for an engine builder and a classic car repair shop. Member here for 24 years! This is the very first car/truck Internet forum I joined. I still used a dial-up modem back then! |
11-21-2024, 03:41 PM | #17 |
New Member
Join Date: Mar 2024
Location: Bend, Oregon
Posts: 10
|
Re: Sourcing 5-6 psi fuel pump help
Think I found the pump I need. Thanks for the help! Another question I had, is the 5/16 port a return line or a vapor line?
|
11-21-2024, 07:39 PM | #18 |
Senior Member
Join Date: Apr 2016
Location: Cypress, TX
Posts: 3,859
|
Re: Sourcing 5-6 psi fuel pump help
There are no vapor lines on the fuel pump.
For those who have dealt with this problem using a fuel regulator, are there any simple and small fuel regulators that have one line in and one line out, and that have inverse flare fittings on both in and out connections, so the hard line can be used with no rubber lines at all? Every time I see rubber lines between the pump and the carburetor I just think I'll never have that any more. Fixed regulator would be better than adjustable. |
Bookmarks |
|
|