My 1996 Cherokee (4.0) consistently stalls after about 15-20 minutes of driving. It just suddenly dies completely and can’t be restarted. If I let it sit for about an hour it starts and drives fine again. When it runs it doesn’t lack power.

At first I thought it was overheating, because my water temperature warning light didn’t seem to be working. I bought a mechanical water temperature gauge, an electric fan to replace the mechanical fan, and a new thermostat (the original was broken). The cooling system works fine now. It stays between 195 and 200. None of this, however, affected the original problem I was trying to fix. The engine runs at normal temperature 10-15 minutes before quitting.

I also changed the fuel filter and the spark plugs. Both of those needed to be changed but didn’t fix the problem.

Just today I learned that I’m probably dealing with an electrical problem. I had my dad follow me until the engine quit. We were able to determine that there was fuel pressure but no spark. Some things we read on the internet led us to believe that the problem was likely to be the crankshaft position sensor. We tried to test the sensor with a multimeter but the test was inconclusive. Two of the pins that were supposed to be an open circuit read as 10 mega ohms. We replaced the sensor. No effect.

Oh, also, the catalytic converter seems to be rattling. Could that have anything to do with this problem?

Any ideas?

If you have no spark, I would concentrate your search around the ignition system, start with the crank sensor, also look at the cam sensor inside the distributor. Also look at your ignition coil. 10 mega ohms is a high reading, try and set your meter to a lower ohm setting. The CS is a fairly cheap item to replace. Your CAt is rattling, May have a plugged cat, look at RANDOM technologies, they offer a high flow cat for under 200.

How do I test the cam position sensor?

How do I test the cam position sensor?



HI, CHECK THE WIRES ON YOU O2 SENSOR YOU MAY HAVE A SHORT, SINCE YOU SAY IT RUNS AND STALLS AFTER A 20 MIN. RUN. CHECK YOU WIRING DOWN BY SENSOR AND BY FRONT DRIVESHAFT, COULD BE FRAYED WIRES. DALE
jeepman600@aol.com if it was camshaft sensor it won't start at all after it shuts off. they will usually restart after if its the crankshaft sensor :smokin:

might be a bad ignition coil.

Thanks for your help everyone.

I talked to a friend who thinks it's the ignition coil. He said that the cam position sensor only affects the fuel injector timing, not the spark timing. A look in the Haynes manual confirmed this. I'm going to try replacing the ignition coil tomorrow, since that isn't too expensive or hard to do. I took the old coil off tonight and noticed some cracks in the molded plastic covering. Maybe that would cause a problem?

if you noticed cracks in casing, that is definately your prob... cracks expand as temp rises allowing it to short until cooled off again

Well, it was the cam shaft position sensor. Replacing the ignition coil had no effect but it was probably still good to do because of the cracks. Replacing the camshaft position sensor cleared the problem right up.

I did this cool test where I took an electric bass pickup (basically a coil of wire) and ran it through my bass amp. I then put the pickup near either the spark plug wires or the fuel injector wires and I could hear them firing. I was able to determine that loss of spark was not the cause of the stalling. The sparks kept firing right up until the engine reached 0 rpm. The fuel injectors, on the other hand, started missing beats after a while. That was surely the cause of the stalling. When it was about to stall I would hear tick tick tick tick tick tick ... tick ... tick ... ... tick (stall). I guess the camshaft position sensor crapped out when it got hot.

So far so good. I’ve driven it for several hours tonight without any problems.