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Old 09-16-2025, 01:47 PM
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Default Fuel pump recommendation

I installed the rebuilt original engine in my Z28. Immediately the fuel pump had fuel pouring out of the vent hole. I installed a brand new from Napa and had flooding issues. Installed a fuel pressure gauge and 12.5psi.

I am looking for a replacement now and any recommendations would be appreciated.

Anyone have experience using a Carter M4685

Anyone have a Delco replacement

Anyone have an original 40669 rebuildable core.

Thanks in advance!
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Old 09-16-2025, 04:01 PM
cheveslakr cheveslakr is offline
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Just bought this one for my 327, haven't checked the fuel pressure so can't verify that. It seemed to solve the issue of hot starts due to overpowering the needle/seat though. It's the cheapest usable pump out there I think, but I did have to reclock it, and tap the holes, since every other hole has threads. I believe it was an 8mm/24 tap???
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Old Yesterday, 09:28 PM
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Bringing this back to life. I have the same ?'s as Steve did. Anyone have any new light to share?
Ty. Doc
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Old Today, 07:20 AM
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I posted on a thread a few years ago about this issue. All of the modern fuel pumps have way too much pressure. I don't know if they all use the same spring from the same manufacturer or what. I went through several trying to find one for the El Camino back in 2017. All were between 10 and 12.5 psi. Ended up getting a low pressure electric.

The only sure fire fix is to use one of the older rebuildable type pumps and purchase a rebuild kit.
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Old Today, 08:03 AM
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Who is recommended for rebuilding/restoring original pumps?
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Old Today, 11:25 AM
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Quote:
Originally Posted by enio45 View Post
Who is recommended for rebuilding/restoring original pumps?
AG Rebuilders

https://agrebuilders.com/
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Old Today, 12:11 PM
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Quote:
Originally Posted by Danzo View Post
Bringing this back to life. I have the same ?'s as Steve did. Anyone have any new light to share?
Ty. Doc
I found a later replacement GM pump which solved my fuel pressure issue.
I sent two old 40669 & 40370 to Fred Ballard for rebuilding. Not sure if there is another rebuilder for the crimp bottom type fuel pumps.

I could have installed a small regulator but preferred using a GM pump.
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Old Today, 12:19 PM
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Quote:
Originally Posted by dykstra View Post
AG can't do the crimp type pumps....Joe
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Old Today, 07:12 PM
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I installed a Carter M4685 two years ago on my 302 and I’ve had no problems. I have not measured fuel pressure, so I’d be curious if anyone else has measured the Carter.
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