Tod Marks

My 91 Ltd 4L died one day. There was no spark. I had recently changed cap and rotor, and plugs. Hmmm so I was advised to change the CPS and I did. Then it started and ran for a couple days. Next morning it wouldnt start so I have change the coil also. I have also rotated the ignition relay with one the same still nothing. Help

Turbo X_J

What are the codes?

tjwalker

Have you re-verified that you have no spark? You should; never assume anything. TEST. If your engine ran for a few days with the different crank sensor, it is entirely impossible that your new crank sensor gave it up. Where did you buy it? I buy my crank sensors directly from Jeep as aftermarket crank sensors are very "hit and miss" with a whole lot of miss.
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Spark: 12 volts from ignition switch to the ASD relay; when the key is first turned on the PCM provides a ground to the ASD relay to energize it, then the ASD relay passes 12 volts to the coil primary side. If no crank sensor signal is generated after a couple of seconds the PCM cuts the ground to the ASD relay (and fuel pump relay too) and that cuts power to the coil (and fuel pump). Key to START and once again the PCM energizes the ASD relay. Now, a critical element is the crank sensor--no signal from the crank sensor and the PCM won't trigger the coil to provide spark.