M38a1 fuel pump and front plate

wilfreeman · Post by **wilfreeman** » Sun Nov 20, 2016 8:37 am

I am installing a military fuel pump on an M38a1 for a friend. It wouldn't fit. I had to enlarge the cutout in the front plate for it to fit. I would assume that this engine came out of a CJ, because they had a different side plate that didn't require the large cutout, correct? I haven't looked for any numbers on the block yet.

Where can I buy the elbows for the military fuel pump fuel and vacuum lines? What are the sizes? Home Depot has some that look similar, but not exact. Would it be acceptable to install copper lines instead of steel since it is so hard to bend and flare?

ROBCDN3 · Post by **ROBCDN3** » Sun Nov 20, 2016 8:49 am

Good morning Wilf. I just put a rebiuld on mine and some of the fittings were bad so I just took them to an auto parts store and matched them up with their stock. They were about half the price of a hardware outlet.
Cheers Rob 1971 M38a1CDN c

4x4M38 · Post by **4x4M38** » Sun Nov 20, 2016 9:05 am

Yep. Ask the desk drone to let you go look in the flare fittings, usually with the brake stuff in a bunch of drawers. They usually have a lot of reverse flare stuff.

And they usually have an assortment of lines with fittings already installed.

Take care,

RICKG · Post by **RICKG** » Sun Nov 20, 2016 10:41 am

Stay away from copper Matt. Easier to bend=easier to break.

wilfreeman · Post by **wilfreeman** » Sun Nov 20, 2016 11:33 am

Thanks guys! I used up the spare fittings I was going to use when I put MY military pump on. The guy I'm helping out is a 78yo vet they wants to get his Jeep running for the Christmas parade. Of course he didn't have the correct spacer, flex hose, bolts, check valve or fittings. Fortunately, I had just bought everything I needed to install my rebuilt pump and was able to help him out. I had to fab the vacuum line going to the pcv valve block out of another steel line that he had which was just long enough. All I have left is to bend the steel line I bought for the pump to carb. Hope to be done in a couple of hours and get it back to him this afternoon.

Post by **wesk** » Sun Nov 20, 2016 12:57 pm

Yes the fuel pump used on the F134 powered civvy jeeps did not require the large hole in the front mount plate required by the military pump. There is also a difference on the right side of the front mount plate where it is beefed up for the heavier 24V generator.

All the pump fittings are listed in the ORD 9 you just to need to look harder for them.

wilfreeman · Post by **wilfreeman** » Sun Nov 20, 2016 5:21 pm

Well, I got the fuel line bent and installed. Went to fire her up and BOTH batteries were dead! I put chargers on them and took an hour to pressure wash the front of the house - might as well mark something off the honey do list while I wait!

Once the batteries had enough charge, I fired her up. I fixed a couple of fuel line leaks and she was purring like a kitten. After it warmed up the trouble started. It ill be idling along fine, start sputtering and die. Fires right up with a pull and push of the choke - it's like its running out of fuel. When I take her for a drive, I get the same result - starts to cut off when it warms up. Starts right up if I push the clutch in, let her roll and pop the clutch in second. Runs fine when it's cold though.

I'm going to check the carb inlet strainer first, but I might end up pulling the carb the next chance I get to work on it. Looks like he won't be making it to the parade this year - today was the last day I'll be able to work on it before then. Maybe Memorial day.

Post by **wesk** » Sun Nov 20, 2016 5:53 pm

Have you checked the fuel tank vent for freedom of air flow? Make sure the tank cap is in the open position if it has a selector inside.

wilfreeman · Post by **wilfreeman** » Sun Nov 20, 2016 8:50 pm

He doesn't have the "correct" cap - his doesn't even have the ears that you grab to turn the cap. His tank also doesn't have the vent filter in the pickup where the vent line would connect in the early a1s. I might go out and put my cap on it and go for a drive to see. Thanks Wes - the cap didn't even cross my mind until you mentioned it.

wilfreeman · Post by **wilfreeman** » Mon Nov 21, 2016 9:29 am

I checked the cap before I left - it IS an INvented one. If I get home early enough I'll run her a little to see if that is the problem.

Post by **wesk** » Mon Nov 21, 2016 10:05 am

There were several caps stocked over the years for m series gas tanks.

Earlu Unvented cap with ears.

The popular selectable vent cap with ears

Later smoothy cap

Plus other vehicle caps often built to the same mil spec:

M37 cap

M135/M211 cap

WWII Repop

wilfreeman · Post by **wilfreeman** » Mon Nov 21, 2016 12:12 pm

His looks like the last pic you posted of the ww2 repro. It doesn't say anything about being vented, nor can I see any wss it would be vented.

4x4M38 · Post by **4x4M38** » Mon Nov 21, 2016 1:20 pm

There's a hole in the right pic just above the S in Supply.

Maybe vent hole?

wilfreeman · Post by **wilfreeman** » Mon Nov 21, 2016 6:04 pm

Oh, I see it now (on the big screen). I was looking on the phone earlier. Yeah, the one he has doesn't have a hole.

When I got home tonight, I took the cap off and drove up and down the driveway (1/4 mile long). It acted like it ran longer with the cap off (after it warmed up). After about 5 min of driving it started to cut off at idle speed. I still think it has a carb problem. One thing is the throttle lever wiggles a good bit. I have the carb I took off of my Jeep when I put the rebuilt one on. I am going to put it on to see if it runs better when I get the time to do it.

Post by **wesk** » Mon Nov 21, 2016 9:51 pm

Have you checked to make sure both Fording valves if you have them are in the open position? Is the carb bowl vent line clear all the way to the crossover tube?