1999 Jeep Cherokee Sport, 4.0 inline 6, 256,000... this past summer my daughter and I were driving, nothing unusual, nothing out of the ordinary... everything just shut off and the check engine light came on... I got stopped, put in park, turned the key off and started it right up... drove a little further and it happened again except this time I noticed the tach rev to about 4500 and shut down... I didn't hear the engine rev, just noticed the tach... same thing: parked, shut it off and it started right up again... drove a little further and this time the tach revved again and went to 0 but then it resumed normal operation for a few more miles and then shut down again... no sputtering, no warning... This time though it wouldn't start when I tried... Got it to my mechanic and he hooked every gauge and tester to it and saw nothing wrong, no warnings or anything... it scared me so I bought something else, but I still have the Jeep...I've driven it a few times since, short trips with no problems... Any clue?

 

first and the easiest, check your battery connections! They should be tight with no corrosion. Also have your battery load tested at advanced auto or auto zone.

You wouldn't believe the problems that can fix. Do that step and report back.

 

There's a guy called 'cruiser54' on this site. He has his own website that lists his tips...
This engine is heavily dependent on clean shiny grounds... the battery. The oil dipstick. An extra you can run. Look his site up. Takes little time. It's free. Buy some steel wool, a steel tooth brush, some electronic cleaner spray, and go at it.
Good luck.

 

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If you can, get it running and wiggle every wire harness in the engine bay and see if it acts up.


Also, visually check the wiring to see if any loom has been chafed thru and any wiring outside of the looms are chafed.


Remove the distributor cap and examine the rotor for damage, cracks in the cap, etc.


There have been cases where the firewall end of the fuel rail chafes through the loom and damages the wiring within.



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The loom should be held away from the fuel rail with a cable tie, like this:

 

Thanks guys!... I'll check that stuff