cranks but no start

[caelin_99jeep]

My 99 wrangler 4.0 manual will not start. After cutting out and shutting off in the middle of the highway after my clutch overheated in a traffic jam, I had to get it towed home. Turning the key only cranks the engine but I get no spark.

Fuel pump works, all the fuses are good, battery is good -this is definitely an electrical issue. I checked all the electrical connections I could find to make sure they were tight and after researching (a lot) I purchased an new PCM but it didn't solve my problem. I have tested the PCM (https://www.wranglerforum.com/threads/easy-way-to-test-your-pcm.418034/) at the important connectors (on the black plug- pin 2 (12volts), 17 (5 volts), 22 (12 volts), 31 and 32 are grounded ) so the PCM is good. I started replacing parts to try to fix it: New distributor (and Cam sensor), new coil, new crank sensor, TPS and oil sensor. I have tried the ASD (automatic shutdown relay) bypass and my coil gets constant power but no pulse. I also replaced spark plugs while I was at it.

What do I do now? I'm trying to pull apart the wiring harness looking for broken wires/ testing for continuity.

 

[Daryl]

Take a close look at your coil for cracks.

 

[caelin_99jeep]

I don't see any, and I have also replaced the coil with a new one

 

[Daryl]

I don't see any, and I have also replaced the coil with a new one

Augh, I see that now. Take a test light and back probe the gray wire at the coil plug while someone cranks the engine over. The light should flash on & off.

 

[caelin_99jeep]

problem solved! after dropping all those parts in and holding the key in the run position I began to hear backfiring coming back through the air box. I concluded that the timing was off. turns out the distributor I had put in needed to be spun 180 degrees. simple mistake. switched it around and it fired right up! the original problem was the crank position sensor had been fried when the engine (not the clutch) overheated on the highway. if you are having similar issues with a no spark continuous cranking, look at the original posts' link to checking the PCM for output at certain pin numbers and if your good, go check the crank position sensor on the top right side of the bell housing right under the firewall.