Why will a 1986 Jeep Comanche crank but not spark?

Answer 1

i would say its your coil check it for spark if no spark then check it for power Ah, but what is the reason for no power? This really sounds like the Crankshaft Position Sensor (CPS), which is notorious for crapping out in these engines. I'm replacing the CPS in my 1988 Jeep Comanche 4.0L tomorrow morning. I have the exact problem noted: I have just replaced the plugs, wires, and distributor (once every ten years!), the thing cranks strongly, and yet I've got no spark. I told my Comanche Brother (also has a 1988) that the Jeep won't start and it feels like a sensor problem ... and he said, "Crankshaft Position Sensor." That's when I remembered the same doggone thing causing me a no-start condition about ten years back. The CPS is about $35 -- I just bought one. When you read up on the CPS, I think you'll find your symptoms noted. Provided that this fixes my no-start condition, I'll be getting another and keeping it handy. Update on the 1988 Comanche that would not start ... it started right up. The funny thing is that I didn't even get to change out the Crankshaft Position Sensor (CPS) yet, because it was too cold for that mess today. But here's the thing: it (the no-start condition) was related to the CPS. Since it was too cold to fool around on the engine block today, I unplugged and replugged the CPS connector a couple of times to see if that would get the truck started -- and it did on the first crank. I read about this trick on-line somewhere, and I'll be darned if it didn't work. That's definitely one to remember! In my truck, the CPS connector is right up on top, just to the driver's side of the line of cylinders, back toward the firewall, and just forward of what looks to be the main wiring harness. Son of a gun.