90 yj 4.2, motorcraft 2150 carb, nutter bypass, brand new hei upgrade. Died on me in the driveway and now won't start. Cranks but no spark from coil. replaced ICM, starter Relay, getting 5.4v/Run and 12.1V/ Start at coil. Getting 12v run, and 12v start voltage at the icm. Resistance on the coil low side is about .8 ohms. Resistance from low to hi side of coil aprox 1,800 ohm. Any help would be greatly appreciated
Cranks, no start no spark issue.
- Thread starter Lineman85
- Start date
Flyer58
YJ Enthusiast
I know nothing about the 4.2 or any conversions but can you check to see if you have voltage at the coil when the key is in the run position and start position? It could be a key switch problem.
I’m dealing with the same thing. Same motor and same carb etc. One thing I haven’t checked yet is the crank position sensor. Not sure why i can’t just bypass these things and turn it into a CJ basically. I changed the ECM. Same issue. Try the sensors. That is next for me.
I ran into a problem like that on my 93 4.0.
My battery was bad. It produced enough juice to crank, but not enough to run the computer.
I have also had a similar issue with a bad coil and a bad crank position sensor.
My battery was bad. It produced enough juice to crank, but not enough to run the computer.
I have also had a similar issue with a bad coil and a bad crank position sensor.