willysmjeeps.com

My M-38 starts, idles and runs great until it warms up. Suddenly going down the road under power it will start to sputter, loss of power and eventually die. I thought it was the carb had junk in it , so I rebuilt the carb. Everything seemed good, my idle improved, smoothness off of pickup and then bam it did the same thing again. This has led me to believe the ignition coil is heating up and starting to break down. Once it starts missing you can shut it down and let it cool and come back and it will start and run fine. I haven't yet pulled the coil and tested it but the behavior makes it my #1 suspect.

My question is around those that may have recently replaced coils. The only thing I can find on the market are the repro coils. The last time I replaced my coil was probably 15+ years ago and I think I was able to source a NOS coil. Has anyone had luck with the newer repro coils and/or recommendations?

I picked up a new cool from eriks, and it has ran just fine. Personaly I think new ones are just fine, as long as you go through a reputable mv dealer.

Before you band aid another guess on what the problem is, finish the troubleshooting process. It's much cheaper that way.

Carry an extra spark plug with you and drive it till it quits. Quickly open the hood and unscrew a plug lead and screw your spare plug into it. Don't worry the shielded cable is all the ground needed. now quickly crank the engine. No spark fix ignition problem. Good spark fix fuel delivery problem.

Better yet, just remove the gas cap and drive the jeep. If it still quits do test 1. If it didn't quit unplug gas tank vent system. Caution there are two types of gas caps. Vented and un-vented. If your cap is the un-vented type then the vent that runs to the air cleaner is plugged. If you have a vented cap then make sure it's built in switch is in the vented position and not the fording position/closed position.