96 Cherokee won't start

Whoknows

Well-Known Member
Joined
Oct 8, 2005
Location
Benson
Ok, this is my father in law's Jeep and I'm trying to help him get it running. I'm going in the morning to trouble shoot it and would like some guidance from you Jeep guys. Here's what I know.

It's a 96 model with the 4.0 and 5 speed tranny. High mileage 250,000+. He said it started running rough and would shut off by itself. He could let it sit and it would start back. He put on a new crankshaft position sensor and now it won't start at all.

If you guys can give me some guidance on where to start looking I would really appreciate it.
 
Check wiring at the cps. Also, if he bought new one from parts store, it may be bad. That is one sensor that is best bought at the dealer. Try exchanging it for another one and hope for the best.

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Do this to diagnose the ignition:
Unplug the 2 wire connector at the coil. Insert a paper clip (jumper wire) into the unplugged connector. Attach test light clip to the positive battery terminal. With the pointy end of the test light, probe the paper clip (jumper wire) while you are cranking the engine over. Observe if it flashes or not.
If it flashes- the PCM and crank sensor are good (coil is being grounded) and you have power present. This means the coil is no good
If it does not flash- either the ground side of the circuit is no good (crank sensor signal to pcm or pcm itself) or the ASD voltage is not present.
 
bulrid8 said:
Check wiring at the cps. Also, if he bought new one from parts store, it may be bad. That is one sensor that is best bought at the dealer. Try exchanging it for another one and hope for the best.

Sent from my ADR6400L using Tapatalk
Click to expand...
Is there a way to test it? He said it was a pain to change out.
 
Jody Treadway said:
Do this to diagnose the ignition:
Unplug the 2 wire connector at the coil. Insert a paper clip (jumper wire) into the unplugged connector. Attach test light clip to the positive battery terminal. With the pointy end of the test light, probe the paper clip (jumper wire) while you are cranking the engine over. Observe if it flashes or not.
If it flashes- the PCM and crank sensor are good (coil is being grounded) and you have power present. This means the coil is no good
If it does not flash- either the ground side of the circuit is no good (crank sensor signal to pcm or pcm itself) or the ASD voltage is not present.
Click to expand...
Thanks, I'll give it a try.
 
Sounds like the typical CPS (crank position sensor) it's on the top drivers side of the bell housing. I just helped a buddy replace his.

You'll need a long extension and a u joint adapter on a socket. Don't recall what size socket but it's about a 10-12 mm I think. We used a 30" extension.

Remove front drive shaft and one person uses ratchet from under neath while the other person guides the socket from above. Cuss a little to get thugs started. Then remove two bolts holding CPS. Unplug it from the harness and plug in new CPS. Then install sensor back unit bell housing. Not too bad a job, just a bit awkward to get to.
 
I was leaning towards something being wrong with the new CPS since it wouldn't start at all after he installed the new one.
 
Check fuel pressure with a gauge. Also, verify there is injector pulse present. You can have all the pressure in the world, but if the injectors aren't opening and closing (pulse), you can't get fuel to the cylinders.
 
Checked connections, charged the battery a bit and it cranked right up. I'm guessing his battery was too drained. Thanks again for the tips.
 
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