JessicatheJeep

Hello, I have a 1987 Cherokee Laredo. Occasionally when it gets hot, it stalls and won't start again until it cools down. It cranks and cranks but won't fire up. I have replaced the ignition coil, ignition control module, the entire distributor, all of my spark plugs and wires and my crankshaft position sensor. I'm completely at a loss and i need my jeep running as soon as possible because i have to move back up to college in a few weeks. I have read many other threads, but nothing seems to help. If anyone could enlighten me on something i may be missing, it would be greatly appreciated! thanks

NorCalJeep

Is fuel reaching the engine? Is the battery okay? Also, if it keeps overheating you should check the thermostat.

JessicatheJeep

Thanks for the reply, but my battery is fine and I've checked the fuel and the pressure is reading what it should be. The engine isn't necessarily overheating, it just dies when it has been run for a while. The gauge is reading within normal parameters

NorCalJeep

If fuel is reaching the engine and you hear it cranking, then it could not getting spark or the CPS is faulty.

Cruiser posts this time to time and could help you with CPS testing

Renix CPS Testing and Adjusting
　
　
"Renix CPSs have to put out a strong enough signal to the ECU so that it will provide spark.
Most tests for the CPS suggest checking it for an ohms value. This is unreliable and can cause some wasted time and aggravation in your diagnosis of a no-start issue as the CPS will test good when in fact it is bad.
The problem with the ohms test is you can have the correct amount of resistance through the CPS but it isn’t generating enough voltage to trigger the ECU to provide spark.
Unplug the harness connector from the CPS. Using your voltmeter set on AC volts and probing both wires in the connector going to the CPS, crank the engine over. It won’t start with the CPS disconnected.
You should get a reading of .5 AC volts.
If you are down in the 3.5 AC volts range or lower on your meter reading, you can have intermittent crank/no-start conditions from your Renix Jeep. Some NEW CPSs (from the big box parts stores) have registered only .2 AC volts while reading the proper resistance!! That’s a definite no-start condition. Best to buy your CPS from Napa or the dealer.
Sometimes on a manual transmission equipped Renix Jeep there is an accumulation of debris on the tip of the CPS. It’s worn off clutch material and since the CPS is a magnet, the metal sticks to the tip of the CPS causing a reduced voltage signal. You MAY get by with cleaning the tip of the CPS off.
A little trick for increasing the output of your CPS is to drill out it’s mounting holes with the first drill bit that just won’t fit through the original holes. Then, when mounting it, hold the CPS down as close to the flywheel as you can while tightening the bolts."

JessicatheJeep

Okay, in the morning I'll check for spark and do the AC volt test on the CPS. I tested the CPS with my ohm meter and it was reading fine, but i'll do the AC test as well to see if i was sold a faulty one. Thanks!

JessicatheJeep

So I tested for spark and for fuel pressure. Both are fine... I'm running out of possibilities that it could be. Could the throttle position sensor, Idle air control valve or the MAP sensor be causing intermittent stalling and no start?

jandsford

Distributor ignition pickup. My 97 was doing the same thing. If I idle for long and the engine compartment gets VERY hot, I would take off and it was like someone just turned the key off. No sputter or chug just die. After cool down, fire up and run just fine. I bought a new distributor ignition pickup and waited for it to do it again. Popped the hood, removed the distributor cap, installed new ignition pickup, started back immediately. I plan on installing louvers in my hood to cut down on engine compartment heat too.