Starting Problems 1991 Cherokee

My 1991 4.0 Cherokee has intermittent starting problems. For the past three days, it will start and restart as needed, then suddenly will crank but not fire. When left overnight, it will start the next morning. This has happened all three days. When it does start, idle is smooth, engine has lots of power and accelerates smooth. After the last occurance I had the vehicle towed to a shop, where of course the problem will not show itself (mechanics are scratching their heads):banghead: . Plugs, wires, cap, and ignition switch have all been replaced. Gas gage is working with half a tank. I can also hear the fuel pump start when the ignition is turned on, then shut down when at pressure. Any help is appreciated!

The two most likely suspects are the ICM (ignition control module) or the CPS (crankshaft position sensor).

This turned out to be leaking fuel injectors. The motor would reach a "flooded" state after the ignition was turned off, and would require an overnight rest before it would fire again.

Wow, never heard of that one before. Good catch. Guess you'll be replacing the injectors....were all of them bad or just a few?