M38A1 Fuel Pumps

cobra5 · Post by **cobra5** » Thu Aug 27, 2020 9:59 am

Since original pumps are hard to find, has anyone found a viable replacement that will work? Searching the web I came across these two.
https://www.quadratec.com/products/917709_03.htm
https://www.quadratec.com/products/917709_04.htm
They are different in appearance but one states it will fit the A-1. However, both state they will fit a CJ3A which is basically the civilian version of the M38. The reason I mention this is because I read where the M38 and the A-1 used the same fuel pumps.
Anyone have some insight?

DaveM38A1 · Post by **DaveM38A1** » Thu Aug 27, 2020 12:00 pm

The thick spacer dictates the fuel pump pressure.
Make sure you have one.

Had a more modern aftermarket dual action fuel pump on the Civilian 64 CJ5 when I got it and the fuel pressure was way too high. Had to run a fuel pressure regulator to keep from always flooding the carb.

Don't know if these will physically fit, but the fuel pressure might be too high also.

Used a rebuild kit on mine for the M38A1, but I've not gotten it running to test it.

Got it from:

http://www.then-now-auto.com/fuel-pumps/

Dave

Post by **wesk** » Thu Aug 27, 2020 12:16 pm

There are many fuel pumps from the jeep line that will fit and work on the M38/M38A1 (L-134 & F-134) engines. Some require some adaptation. The most common civilian dual action pump is the CJ3B F-134 unit that matches the engine but needs the vacuum lines adapted from tubing fittings to hose tubes. To regualte the pump's output pressure Willys went with varied thickness pump to block spacers. So when you substitute a civvy pump and it's pressure is incorrect with the original 9/16" thick spacer then just fabricate different thickness spacers to come up with the desired pressure.

There are about 6 different military dual action pumps used on the M38/M38A1/M170 series jeeps. The military simply kept superseding to the later pumps in their supply system. Yes they all will work on all three jeeps.

If you do not use vacuum wipers then you can certainly substitute a civvy single action pump. Just work in the correct thickness spacer to regulate pressure correctly.

cobra5 · Post by **cobra5** » Thu Aug 27, 2020 1:08 pm

Ok I'm going to go with one in the link. Anyone else using it and know the thickness of the required spacer? I searched the forum and I think I found my answer 1/8 spacer. Is this right?
https://www.quadratec.com/products/917709_04.htm

WillysMotors · Post by **WillysMotors** » Thu Aug 27, 2020 8:13 pm

Rock Auto is about $80

Post by **wesk** » Thu Aug 27, 2020 8:19 pm

I searched the forum and I think I found my answer 1/8 spacer. Is this right?

Can't say either way without knowing the AC part number of the fuel pump.

4x4M38 · Post by **4x4M38** » Thu Aug 27, 2020 10:17 pm

The correct pumps are not hard to find.

First rattle out of the box...

https://www.ebay.com/itm/M38-M38A1-WILL ... 2917220032

cobra5 · Post by **cobra5** » Mon Aug 31, 2020 5:16 pm

4x4M38 wrote:The correct pumps are not hard to find.

First rattle out of the box...

https://www.ebay.com/itm/M38-M38A1-WILL ... 2917220032

That ended back in Apr.

RonD2 · Post by **RonD2** » Mon Aug 31, 2020 6:29 pm

Nope. August not April. How do I know? Because I bought it. Needed a re-buildable core for a spare. A little pricey at $87.50 (delivered, with tax), but patience got the best of me.

4x4M38 · Post by **4x4M38** » Tue Sep 01, 2020 10:40 am

My point.

They are around.

George has them but requires a core or $100 core charge.

https://www.armyjeepparts.com/p-1807-fu ... gIR0vD_BwE

Have you tried calling the suppliers? There’s no way they have everything listed on line. If you’ve ever seen photos of their inventory you can see that. Army Jeep Parts, Midwest Military, Brent Mullins Jeep Parts, Quarter Ton Military, etc.. Plus you have a chance to talk to some really nice and knowledgeable folks in most cases, and possibly develop a relationship. That’s important in any hobby, including this one. Those guys all know each other, and can help.

There is one on eBay, from Bulgaria? You are on your own there.

cobra5 · Post by **cobra5** » Tue Sep 01, 2020 10:43 am

RonD2 wrote:Nope. August not April. How do I know? Because I bought it. Needed a re-buildable core for a spare. A little pricey at $87.50 (delivered, with tax), but patience got the best of me.

That's strange because when I click on the link it clearly shows it end April 29, 2020.

Updated: Never mind I went further back and opened the original listing and it shows Aug. I went and tried the link again and it now says Aug. Don't know whats going on but I should have taken a photo of it.

cobra5 · Post by **cobra5** » Tue Sep 01, 2020 10:47 am

4x4M38 wrote:My point.

They are around.

George has them but requires a core or $100 core charge.

https://www.armyjeepparts.com/p-1807-fu ... gIR0vD_BwE

Have you tried calling the suppliers? There’s no way they have everything listed on line. If you’ve ever seen photos of their inventory you can see that. Army Jeep Parts, Midwest Military, Brent Mullins Jeep Parts, Quarter Ton Military, etc.. Plus you have a chance to talk to some really nice and knowledgeable folks in most cases, and possibly develop a relationship. That’s important in any hobby, including this one. Those guys all know each other, and can help.

There is one on eBay, from Bulgaria? You are on your own there.

They are around but don't seem to come up as frequently as one would think.

cobra5 · Post by **cobra5** » Thu Sep 10, 2020 10:03 am

wesk wrote:
I searched the forum and I think I found my answer 1/8 spacer. Is this right?
Can't say either way without knowing the AC part number of the fuel pump.

This is the pump I bought.

https://www.rockauto.com/en/moreinfo.ph ... sn=1&jsn=1

Post by **wesk** » Thu Sep 10, 2020 11:00 am

That site does not offer a AC part number for which their odd number pump is a sub for. You are back to experimenting with spacers till you find one the gives the correct operating pressure.

RonD2 · Post by **RonD2** » Thu Sep 10, 2020 11:09 am

That site gives this Alternate/OEM Part Number(s): 5594698

Isn't that the AC number?

Maximum Pressure Rate (psi) 3.75
Minimum Free Flow Rate (gph) 15 GPH @ 1000 RPM
Minimum Pressure Rate (psi) 2.5