I have a 1999 Jeep Cherokee Sport 6cy that I love . It has 180000 miles on it.
For the last year it won't start when the motor is warm .
When it's warm and you turn the key to the accessory position , if the temp gauge doesn't move you can crank it and it won't turn over . Sometimes If you wait a few minuets and gauge goes up ,it will start .
It will also stall if your driving and the temp gauge drops to far .
The electric fan hasn't worked for like 3 years and I know it works because I jumped it and it went on. The relay in the fuse box is also good.
I did replace the cps because I didn't notice the temp gauge thing ,and that did nothing .
Any help would be Greatly appreciated .

 

hey Chain....you can test the temp sensor on the engine....unplug the connector and measure resistance across the terminals....engine cold = high resistance....engine warm/hot = low resistance....or you can remove the sensor and test in bowl of water...

.....this applies to the renix engine, but troubleshooting tips still apply..... http://www.lunghd.com/Tech_Articles/..._Diagnosis.htm ...and.... http://www.lunghd.com/Tech_Articles/...iagnostics.htm

"Basically - temp sensor functions by providing a resistance-to-ground circuit that the computer (ECU) uses to determine how much fuel the engine requires. (The hotter the coolant - the lower the resistance.) The resistance of the sensor is read by the ECU which in turn adjusts the air/fuel ratio as close to 14.7:1 as possible. When a coolant temperature sensor fails (open circuit / no continuity) the high / infinite resisitance will cause the ECU to falsely read the max low temperature of -40 degrees F. The ECU then tells the injectors to enrichen the fuel mixture because it thinks the temp is really cold when it really isn't. A short to ground would cause a 'no-resistance' fault causing the ECU to think the coolant air temperature was extremely hot and lean out the fuel mix.

Unlike late HO engines; RENIX engines do NOT have a combination coolant temperature sensor that also feeds the gauge! RENIX vehicles use a SEPARATE sensor located on the back half of the head, driver side."

....good luck!