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Got my M38A1 back together today with all the new steering components installed.

No more death wobble! And it steers like it is brand new and I can take it up over 50 mph! Thank you guys so much for the help on that issue.

However the stuttering problem reared its ugly head again. I think I figured out what is wrong though.

About a month ago before I took the M38A1 apart I noticed that my fuel tank was full of rust and other pieces of junk. I was experiencing some stuttering issues so I cleaned the tank out and re-coated it.

I also took the carb apart and cleaned it up, it had some gunk in it. The rebuild kit used I believe was the one from Midwest military (the PO supplied the rebuild kit) because it looked like a quality kit.

Around 2:00 pm I started the jeep and it idled great. When I took it for a drive though about 3 minutes of driving down the road it started to sputter and die. I was able to baby it home.

Since I thought it was a fuel delivery issue I installed some clear tubing near the carb inlet so I could watch the fuel flow.

After I installed the clear tubing I started the jeep again (about an hour later after parking it). The jeep idled fine and I could see gas being pumped through the fuel line into the carb.

I shut the hood and took it for a drive again, about 5 minutes later it started to sputter and then it died. I pulled off the side of the road and opened the hood.

I could see there was no fuel in the line. It is hot here, we have had 60+ days of triple digit temps. So I thought it could be either vapor lock or vacuum lock. I removed the gas cap and was able to drive about 10-15 more minutes with no more stuttering problems.

When I would reach a stop sign though it would idle rough and almost die, I had to give it a little gas to keep it going. Once I was moving though there were no problems. Got it up to 50 mph and i could tell I could push it a little further but didn't want to push the engine that hard. 45 mph feels much more comfortable.

I pulled into my driveway and let it idle. It was idling rough so I grabbed my camera and opened the hood and filmed the fuel delivery. After about 3-5 minutes it smoothed out and idled just fine.

At this point I noticed the flexible fuel was hot down near the fender, I also noticed the exhaust gasket that goes between the header pipe and the muffler pipe was leaking and putting out hot gases into the direction of the fuel line.

So does this theory sound correct?

Fuel tank vent was clogged and not venting causing a vacuum lock. Once the gas cap was removed the vacuum problem was reduced allowing fuel to be delivered. The rough idling problem was caused by a very hot day and hot exhaust pouring into the engine compartment causing the fuel line to vapor lock at lower rpms because the pump wasn’t pumping enough to overcome the vapor lock at idle. Once I parked it and opened the hood the hot temps trapped under the hood were released allowing the fuel line to cool down enough so that the vapor lock went away resulting in normal idling conditions.


Picture of the place the exhaust was coming out.




Here is a video of it idling rough about 30 seconds after I pulled into the drive way. About 2 minutes later it went back to idling normal.

http://www.youtube.com/watch?v=iB49tGwGPFA


Any thoughts?

That's all very possible but only with your plumbing. Is there a reason you do not have your fuel feed line plumbed the original way? It originally went around the front of the engine .

That's all very possible but only with your plumbing. Is there a reason you do not have your fuel feed line plumbed the original way? It originally went around the front of the engine .

It was plumbed that way when i got it.

Gonna go and see if i can find a picture of how it should be plumbed unless you have any?

Does any one have some good pics of the fuel line circled in red and how it fits around every thing up to the carb. Its hard to tell how exactly teh fuel line snakes its way up the carb with this diagram.