Hello,
I'm new here. I bought a 89 YJ 4.2l a few years ago. The body and chassis are in great shape (California jeep). the engine on the other hand needed work. I was able to get it running and driving good, until about a year ago. It has progressively gotten worse since then, on to the issue.
When it started happening it took a lot longer before it was a problem, now 10 to 20 miles is all it takes sometimes less. It starts and runs fine for the first 10 to 20 miles, then it hesitates, sputters, and will stall at idle. I can restart it and it will sit and idle fine, give it gas and it sputters or stalls. if I push it to far, I have to let it cool for 30 minutes to an hour before it will start again. it acts like something is getting hot and causing a problem.
What I have done:
replaced Distributor today
replaced cap & rotor, plugs, wires, coil (twice since I bought it, less than 10k miles)
replaced all fuel filters including in tank filter
removed the Howell EFI system I had installed, replaced with weber carburetor and problem still there, reinstalled EFI
replaced fuel pump for EFI
Added fuel pressure gauge to ensure proper pressure
I'm sure there is more I have left out.
I know it can't be fuel management, being I have the problem on EFI system and a carburetor with 2 different fuel pumps.
I finally decided to take it to a mechanic and first they fixed the rough idle issue (because I did a sloppy job putting the throttle body back on) and never look at the issue I brought it in for. After being at the shop for 2 months and they still hadn't looked at it, I brought it home and I'm going to try to fix it myself, again.
Any help and suggestions are greatly appreciated. I hope to get it fixed so I can drive it down to the local beach, but currently it may be come and artificial reef or meet the crusher.