Carb, ECM or Iginition Module? YJ stalling and running rough when warm

[Fish!]

Several weeks ago my 90 YJ 4.2l started acting strangely and it seems to be getting worse as time goes by.

It'll start just fine (aside from several pumps of the gas pedal when it hasn't been started in a few days) and idle and run, but just as the engine is getting to a good operating temperature it'll stall. When I say 'stall', I mean it just shuts off. No hesitation or stumbling, just... off. The first couple of times it happened, I though the negative battery connector had come off. It's that sudden. But all my electrics stay on, so it's not that. It'll usually start right back up in a few seconds but a couple of times it really didn't want to and took several minutes. The colder it is outside the longer it seems to take to restart.

Once it's warmed up everything seems fine. Until it gets a little too warm. Then it losses massive amounts of power and starts to stumble and choke. It'll idle just fine when it's hot but as soon as it's under load it'll cough and ping like crazy.

At first I thought it was the stock choke was sticking in that Carter carb or something, but the way it stops makes me think it's not fuel related.

Any thoughts?

Thanks.

 

[69jeepcj]

I honestly am not sure, but since you have no replies yet I will try. I don't think its any of the items listed in your post title, maybe the carb. I would start by making SURE the choke is working correctly, then start looking for vacuum leaks. It could be fuel related if the fuel pump is getting ready to go out (check you fuel presure). When is the last time you gave it a good tune up, plugs, wires.

 

[Fish!]

My first thought was that the choke wasn't working. That 2bbl Carter has an electronic choke with a solenoid right? Is there any easy way to check to see if it's working correctly? I had plans to drop in a Weber at some point. That point might be now.

 

[69jeepcj]

I dont know anything about those carbs, so I couldnt tell you. If they were side by side I couldnt tell you which was which. I would check you fuel presure before buying a new carb just to rule out the pump. Most vac gauges can be used as a presure gauge as well, I got my gauge at autozone for about 10 bucks I think. take your line apart and hook the gauge to it and try to start the engine, see what the presure go,s up to on the gauge. I think you want 55psi(not positive of that tho). lower readings would suggest the pump is going out. Im suprised know one else has chimed in on this. Lots of wrangler owner on the site