I have a 2001 jeep cherokee sport "6 cyl". I had a remanufactured engine installed a few months ago. After the first month my check engine light came on. Then about every 2 weeks or so I would be at a stop light light and the engine would just quit running. Electricity is still on. It would start right back up. And engine sounds good, but just quits running. I took it back to the shop and they ran diagnostics and asked me to put a new gas cap on - so I did. I took it back again and they said it was an O2 Censor so they replaced it. I got about a mile away from the mechanic shop and had stopped in the street and the engine just shut off. Only this time it would not start. The engine would just turn over but no start. The mechanic picked up the jeep an hour later and it started right up. Any ideas? Just about everything under the hood is new "except the wiring harness". Maybe fuel pump?

 

Have your mechanic check the output (pulses) of the crankshaft position sensor (CPS). It may have been damaged during the new engine install. IMHO anytime you do engine or transmission remove/install, it'd good practice to install a new one. Do the check when there is a no-start condition.

If it was just a stall-and-restart problem, I'd say it was the IAC (idle air controller) but your no start required a cool-down period so I suspect the CPS.

As with all remote diagnosis, it's purely a quessing game based on known faults with this vehicle.

 

Well how about that. I called my mechanic to give him your recommendations and before I got a chance to say anything - he said he was replacing the "crank position sensor". They did put a new one on with the new engine, but he thinks it is defective. Crossing my fingers.... Thanks for your recommendations.