Help!!! Jeep turns over but won't fire!

My 94 XJ SE 2Dr 5spd 4.0L is in the shop, getting body work done, but it won't start. My mechanic is not the best with electrical but he is a Mopar guy and we have done all the obvious stuff and are stuck. I am planning on having a Jeep specialist take it in a couple days, unless we can figure out.

Installed a brand new CPS sensor.
Also: new coil, cap, rotor, and plug wires.
It is getting fuel we can smell it.

It seems there is no spark getting to the coil. Starter is a year old and it turns over great. Not even attempting to fire so it can't be plugs.

Are we missing a ground wire that needs to be checked? Cleared the computer by grounding the negative line and checked today there are no codes.

My battery is old but good enough. It has been on his charger.

It was starting fine for me last december. It got towed for parking, I moved it and then my blower motor stopped working, but it used to squeal. Then I had a guy move it with a dolley to do body work and when he got it, it wouldn't start, and he screwed around with it. I moved it to another guy, it has been in his dry shop forever. I initially thought condensation could have shorted things out, my blower motor is still dead and needs to be changed.

He checked all the fuses and pulled main ones one at a time to see if that did it.

I feel like I have ruled out the usual suspects here and need any other ideas to try before I move it to another mechanic.

Thanks all!!!

The CPS or CPS wire circuit is the obvious suspect, but some random paint sniffing body man screwing around with stuff under the hood is also a good suspect.

Any weakness in the battery can cause starting problems. But it's supposed to be charged up..

There is another sensor in the distributor which times the spark, if it's bad then it's like a failing CPS.

Personally I'd look it over for something missing as many places as it's been. Sounds like it was impounded, then towed a few other places. Not uncommon for some to happen by and snatch something, not to imply anything about you body shop but I've know a few who take fuses and relays out of one car to get another running and out the door. But the XJ is old enough it shouldn't be a target.

Maybe I'm overthinking and it's as simple as the coil is bad.

He is really good at body work, but that's not all he does, but is a younger mechanic.

He pulled the electrical disc out of the distributor and it looks fine.

My theory is the gas is old and crap. The tank is near the red, and has been for 4 months; and in 3 months it has not been started this whole winter. The tank has always been sealed and no moisture, but I hear ethanol in the gas can screw with it, just 87 octane. I know it is a 20 gallon tank and the gauge reads 16, so I have 4-5 gallons at the bottom. I plan to add 5 gallons of ethanol free 93 octane tomorrow, tap the tank, tap the pump, jump up and down on the bumper, try to start it while hitting the pedal. I think even though I am not hearing it attempt to fire does not mean there is no spark, the fuel pressure/quality could be bad.

We did not verify there is no spark by pulling a plug and seeing if it arcs. We may do that first to confirm. If there is a better trick please let me know tonight.

Check the fuel pump ballast resistor and fuel pump ground located in the rear cargo area behind the plastic panel where the spare tire mounts.

Im havin same issue with mine and havent figured it out yet been goin through everythin had fuel n all but no spark

Pretty sure OP's heep is late enough that the ballast resistor was non-existant from the factory.
I suggest swapping in another (known good if possible) crank sensor. Consider checking your ignition switch and wires too.

thanasi85 said:

Check the fuel pump ballast resistor and fuel pump ground located in the rear cargo area behind the plastic panel where the spare tire mounts.

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If you pull the plugs, do they smell like gas, or are they wet? Wet fouling of plugs is a common problem in situations like this. Pull the plugs, use compressed air in the cylinders to dry them out. Replace the plugs with a cheap set of Champions.

CHECK GROUNDS FIRST!! I'm more familiar with the Renix system, but most 4.0s have a ground stud near the firewall on the passenger side of the block. Make sure there is also a good ground between the engine and body. Won't hurt to run an additional ground wire from that stud where the other grounds are to the body, but make sure there is a ground cable from somewhere on the engine to the body, usually near one of the motor mounts. Even if the connections on any of those are tight, I'd pull them, clean real good, then put back. Sometimes that's all it takes.

Check the connector to the ignition module also. I had one with a weal spark, too weak to crank the engine. Turned out to be a very slightly corroded connector to the ignition module. The module rarely goes bad on these, it's usually just that connector. I sprayed with contact cleaner (both sides) and was on my way.

farna said:

CHECK GROUNDS FIRST!!

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That being your first suggestion kind of gives it away that you are a Renix person haha

I just went through all of this for a few weeks changed ton of parts finally went out today and got n engine harness from junkyard 30 bucks put it in fired right up

brandon05990 said:

I just went through all of this for a few weeks changed ton of parts finally went out today and got n engine harness from junkyard 30 bucks put it in fired right up

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That's pretty drastic. I can see how older harnesses could fail.
Toyota was the worst, had a supra where about every plug and connection crumbled. Finally got rid of the car when the harness was chewed by vermin.

Okay y'all I have an 1989 XJ 4.0 yesterday I put a new fuel pump in the tank and I have the same situation however the difference is I have a brand new battery from O'Reilly and I get crank but no fire however I don't smell fuel at all any help

I tried my additional/used MAP but, this exchange made no difference in my engine's ability to start. I then exchanged the coil and the engine started. It was either the coil change or, the tension bands the round coil terminals contact that are built into the ICM housing. I found these had a little debris on them so, I wrapped a straight blade screw driver with several layers of paper towel and rubbed the debris away. If I could have found my dielectric grease I would have used it.

My issue I had was a camshaft position sensor...not the crank position sensor. Located in the distributor.