I have a 93 xj cherokee with the 4.0 and auto, 6 1/2" lift on 33's. The other day I went for an easy casual ride in the woods and it started acting like it was loading up on fuel, sputtering and backfiring and would have to rev it up a few times to clear it out and would run fine. I've been having problems with it ever since. You can start it and let it sit and run and it will start running like crap and die. Start it back up and it does the same thing. If you try to catch it before it dies, when you give it gas it dies. I've also noticed that even on cold starts after about 5 seconds after you start it the motor will rev and the electric cooling fan will kick on. I don't know where to start, please help.

 

could be vacuum leak or fuel filter, but with the fan kicking on you may have a short somewhere

 

Sounds more like a short with fan kicking on.. or maybe ground dropping out? Might want to check for any loose/corroded grounds.

 

I am going to chase some wires down and see if I can find anything wrong. Could there be a temperature sending unit somewhere or electronic component that could go out and cause the problems?

 

It does sound like an electrical problem, but there's no guarantee of that...

The fuel pressure regulator could be toast, causing it to run rich, and of course if you burn more fuel it's going to get hot which might explain the fan (though if the temp gauge reads normal, I'm not sure). Do these have return lines for the fuel? Maybe that's pinched off or clogged.

 

Well I'm going to put a new fuel filter on it and see what happens. Then work my way up to the fuel pressure regulator and so on. I'm not in a real big hurry because I'm in the process of putting new floor pans in it and doing some body and paint work now. I will get it figured out eventually, just thought I'd try to get some other opinions.