lordwhitewolf1981

he has a 90 jeep cherokee 4.0 and he left his house this morning and got 4 blocks and it died, we checked all the wires and hoses we could, made sure it was getting fuel, replaced ingition control modual, checked coil pack ( showed 6.36 and new was 6.86). plugs and wires, distributer cap and rotor, and fuel filter was replaced this last summer. still wont start anybody got any ideas?

hypersthenos

Change the crack position sensor. Mild PITA but can be done from underneath with long sockets & wobble. Make sure to route new wire into the little retainer at the back of the engine to prevent damage. Many posts on here that give much detail on the procedure.

89Renix

X2 on CrankPS, You beat me to it

cruiser54

CHECK the CPS first. A hillbilly way to do it is unplug it and plug it back in. Works sometimes.

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.
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 range 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.