Mechanics

JEEP CHEROKEE SPARK PROBLEM

1992 Jeep Cherokee • 262,481 miles

I have a 1992 jeep cherokee 4.0L 2WD about 2 weeks ago the crankshaft sensor got broke and I didnt know about it. I replace the cap, rotor and the coil. The plugs and wires got replaced 3 months ago and I got a new starter about 5 months ago and I new battery 7 months ago. I have now replaced the sensor and it still didnt want to start and I got someone else to try to start it and it started smoking from the ccv I got that fixed. What would make my motor turn over but not start?
Avatar



All "crank, no start" conditions are approached in the same way. Every engine requires certain functions to be able to run. Some of these functions rely on specific components to work and some components are part of more than one function so it is important to see the whole picture to be able to conclude anything about what may have failed. Also, these functions can ONLY be tested during the failure. Any other time and they will simply test good because the problem isn't present at the moment.
If you approach this in any other way, you are merely guessing and that only serves to replace unnecessary parts and wastes money.

Every engine requires spark, fuel and compression to run. That's what we have to look for.

These are the basics that need to be tested and will give us the info required to isolate a cause.

1) Test for spark at the plug end of the wire using a spark tester. If none found, check for power supply on the + terminal of the coil with the key on.

2) Test for injector pulse using a small bulb called a noid light. If none found, check for power supply at one side of the injector with the key on.

3) Use a fuel pressure gauge to test for correct fuel pressure, also noticing if the pressure holds when key is shut off.

4) If all of these things check good, then you would need to do a complete compression test.

Once you have determined which of these functions has dropped out,
you will know which system is having the problem.

Wrenchtech
Jan 19, 2013.