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robtco99 09-23-2013 12:08 AM

Stalling/shutting off after warm up
I have an 01 cherokee 4.0, auto, 4x4, with 99k. It runs and drives fine except that it will stall/engine will shut off after the jeep seems to warm up. It will start right back up after it stalls and will usually only stall once. It used to do this randomly, but it does this every time that I drive it now. It doesn't buck, surge, or anything, it's almost like someone turned the key to off when it dies. The rpms don't matter either when it stalls it could be idling or you could be driving on the highway.

The jeep throws no check engine light and has no codes. The gauges all work fine, it has good fuel pressure, and it starts right back up, so it probably isn't crank sensor.

The fuel pump has been replaced recently with a bosch, a new battery, a Mopar IAC valve, new TPS sensor, tune up, etc have all been done recently.

I'm at a loss what is wrong with it. any ideas?

zfender14 09-23-2013 08:38 AM

I had this problem in my yj. I put up with it for a while under the assumption that the fix would put a dent in my wallet. The fix was painfully simple once I figured it out.

Change your spark plug wires. Mine had worn out and the engine heat would kill the spark, killing the motor. It would start fine with a cool engine and would usually start back up after the motor would die.

If you leave it I would guess that eventually the motor will only come on for 30-60 seconds before it dies again.

CJ7-Tim 09-23-2013 12:20 PM

Test the fuel pressure, it should have 49 +/-5 psi.

What makes you think the Crankshaft Position Sensor (CPS) is good ? Have you tested it ? One of the most common causes of heat related stalling is a faulty CPS. Have inspected the battery wires and Load Tested the battery ?

tjwalker 09-23-2013 07:46 PM

It really could be the crank sensor.

It is not uncommon to have your exact symptoms (stalling but starting right up) with the front end of a crank sensor problem. And even more so is the fact that crank sensors are suspect for "thermal" (heat related) failure, which is what you are experiencing.

And also this tidbit of crank sensor trivia. Crank sensors will only set a code/CEL about 30-40% of the time. The rest of the time, the failure escapes the OBD system.

If you do replace it, do yourself a big favor and buy a Mopar unit directly from Jeep. Aftermarket crank sensors are very "hit and miss" with a lot of miss!

robtco99 10-01-2013 09:15 AM

I replaced the CPS and everything seems to be fine now. The part from the dealer is about $80

I thought the cps was good because all the dash gauges worked, no check engine light, had good fuel pressure, and it would restart after stalling. It turns out that the crank sensor was just starting to go bad and would act up when it got hot.

Definitely a pain to change I took the advice to remove the front drive shaft and it made it considerably easier to get to.

CJ7-Tim 10-01-2013 06:54 PM


Originally Posted by robtco99 (Post 16462345)
..... turns out that the crank sensor was just starting to go bad and would act up when it got hot.

This is most definitely one of the first signs of a weak CPS. Glad you got it fixed before your were stranded someplace with a non-running Jeep.

The time now is 02:46 PM.

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