Weird Problem

Ok this might take a while so hear me out. I have a 91 limited with about 140k on it. After it has been running a while or it is hot it will die. It will usually die when I am coming off the highway or sitting a stoplight but it is starting to do it when i am driving. Just the engine will die. All electrical systems will continue running and there seems to be no interuption in electrical power so that leads me to believe that the problem is not electrical. Most of the time it will start back up with a little persuasion but sometimes it will not start at all. I will then come back about an hour or so later and It will start fine and run great. I am totally in the dark here so any help would be great.
Thanks a bunch
Casey

Sounds like classic Crankshaft Position Sensor is starting to failure. I believe they're available on the aftermarket these days, so it shouldn't be too much.

The CPS is located at the rear of the drivers side of the engine, at the bell housing (it gets it's reading from the flywheel). Just follow the wire from your fuel rail to it. Helps to have small hands when you change it.

Sequoia

How hard is that to do. You said bell housing-does that mean engine removal?

I don't know about a 91 but on my 97 it's at about the 10 to 11 o'clock position as your sitting in the drivers seat or looking up at it from the back side of the bell housing. Looks like a real PIA to replace due to the close quarters.

I sort of had the same problem with my 93' in the summertime. I would drive if for say 20 min. park at a store, come back out and it would not start. The I would lift the hood, let if cool down for about 10-15 min. Vrooom, it would start.

I did the following, but not everything had a major effect on the probem.

CPS sensor, MAP sensor: Still had problem just not as often

Later that summer found out my water pump went out and replaced the temp sensor. The Rad would boil over and the idiot light would not turn on. After this I have not had a single problem with it, but then again the outside Temps were under 100 by then.

I'll see what happens this summer. Fresno gets HOT!!

HTH

You can do it without pulling anything man, it's just a little tight. Once you remove the two bolts on the sensor it pulls right out (it's not in very deep)

The CPS isn't that hard. I used a 1/4" socket wrench with long extensions and a U-joint. Get it from behind the bell housing on the drivers side. Just be patient, BTW I have a 5 spd, so it might be harder with the AT.

Thanks for all the help you guys are awesome

Just did mine on an auto and I used two to three 6" extensions. Can't get my hand on the bolt so the trick is to find it by feel. You need one of those 500,000 CP trouble lights and a helper to guide me would have been nice

Casey, I had the same problem. It started just like yours is doing now. But eventually, it got really bad and would die and not restart immediately, sometimes not all. Finally it died and it sat for two weeks. I don't remember who it was in the club, but they suggested it might be the CPS. One way to narrow it down is, when it dies, unplug the connection to the CPS, and then immediately plug it back in. It is located on the drivers side by the firewall at the end of the valve cover. That is what I did, and it started right up. Then I replaced the CPS unit. I have not had that problem ever since. I did talk to my jeep dealer, and the CPS problem is very common. Hope this helps. You can change it yourself. Like the other have mentioned, it is a little tight. I found it easier if I put my XJ on ramps so that I could sit up a little.

Casper

My dad had a similer problem with his 93xj, he had a jeep dealer in Atlanta put a bunch of parts on it that didn't fix his problem. When he got back to Michigan, and it was STILL BROKE I hooked up my scan-tool and after running the engin for a half hour I checked the coolant temp sensor it was reading 28 deg.F the engin was so hot you could hardly touch it. Replaced sensor, fixed problem when you started his it would chug and run very rich (lots of black smoke from tail pipe)hope this helps

JEFF said:

My dad had a similer problem with his 93xj, he had a jeep dealer in Atlanta put a bunch of parts on it that didn't fix his problem. When he got back to Michigan, and it was STILL BROKE I hooked up my scan-tool and after running the engin for a half hour I checked the coolant temp sensor it was reading 28 deg.F the engin was so hot you could hardly touch it. Replaced sensor, fixed problem when you started his it would chug and run very rich (lots of black smoke from tail pipe)hope this helps

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That must have been my problem, with my 93'. With that I think I won't be having any start problems this summer, unlesss I do something stupid.

Thanks for the input.