my 1989 4.0, auto 4x4 keeps stalling once it warms up.
When cold it stalls right up, but after idling for 6 minutes it dies and then will not for at least another 10-15 minutes. It just replace the distributor less than 90 days ago and I had the Ignition control module checked today and it was good. I think that it could be the coil, or cam position sensor. Any Ideas? This is my sons jeep and broke down while at college over 3 hours away. Would like to know what it is since I can't have a lot of time while diagnosing it at his dorm.

Thanks

Check the IAC. It sounds like it is sticking and needs cleaning or replacing.

What is the IAC?

More info on my original post, when it dies, there is no spark at the distributor, but it will start 10 minutes later and run for about 5 minutes before dieing again. Any suggestions?

What is the IAC?

More info on my original post, when it dies, there is no spark at the distributor, but it will start 10 minutes later and run for about 5 minutes before dieing again. Any suggestions?
IAC = Idle Air Control.

But if you have no spark, it could be one of the sensors you mentioned.

Have your son check the codes (turn key ON-OFF-ON-OFF-ON within 5 seconds & watch engine light). Even if the check engine light is NOT on, there could be some codes stored.

That's what happened when my wife's 92 had trouble. Turned out to be the Crankshaft Position Sensor (mounted on Bell Housing). I was steered to this problem by the codes I got when it would not start.

Take Care,

you need a computer reader for the 89 and 90, but I agree with the crank shaft sensor.

I had my son replace the ignition coil today on the advice of a local mechanic. It did not fix the problem.
If it was the Crank position sensor, would the Jeep still start? I know it won't if the Cam position sensor fails.

If the CPS is no good, it will prevent spark from occurring. It can be ok when cold then open or short when it warms up.

This happened to my '88. I could run for 10-15 minutes and then the engine would quit. I had to ait about 20-30 minutes for it to cool down enough to start but it would only run few minutes again. Changing my CPS cured it.

I just returned from Savannah, GA, where my son's jeep is broke down in his dorm parking lot. It looks like it is the Crank Position Sensor.

When cold the CPS ohm's out at .255 on 2k setting of ohmmeter and 198 on 200 ohm setting. I remember reading it should be approx 275. It was only giving off .001 volts (on 2 Volt setting) while cranking. Should be between .5 and .8 volsts. The CPS was reading 3.84 volts while ruinning. And the voltage drop across the fule pump ballest resitor was 3.86.

After the jeep started and ran for about 10 minutes before stalling out again I repeated the steps above. CPS ohm's out at .222 on 2K setting and 195 on 200 setting. It still only got .001 volts on 2 volt setting while cranking.

Sound to me like it will need to be replaced, so I will have to tow it home to make the repairs since I cannot do them in his parking lot, and I do not know any of the mechanics in Savannah.

I just wanted to close this thread. The stalling turned out to be the crank position sensor, once i replaced it the jeep started and ran fine.
Also had low fuel pressure which turned out to be a rubber hose in the fuel tank.

I just wanted to close this thread. The stalling turned out to be the crank position sensor, once i replaced it the jeep started and ran fine.
Also had low fuel pressure which turned out to be a rubber hose in the fuel tank.

I realize this is after the fact, but the reason your cps voltage was wierd was because it generates AC voltage. Dc won't register right.

Good job getting it going anyway!