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HELP I SEARCHED MOVING IN 2 DAYS NEED MY XJ TO RUN!!!

89RockHeep

NAXJA Forum User
Location
Fremont,CA
89 jeep cherokee pioneer 4.0 So as it says its having a cut out problem. and im moving and that truck is whats moving me! so. what its doing: dying. just randomly. il be going along flat road no bumps and it just dies and wont start. let it set over night its fine. but will do it again. so far the only thing i know is that its a spark issue.
the only thing wrong ive discovered so far is that when the problem happens, the ICM has no ground, well atleast on the top where the coil plugs in, theres no ground.so far ive replaced:ICM, Fuel pump and cap+rotor
please please please help im moving out of state in 2 days and need this truck to run
 
have a look at your engine ground strap that is braided and goes from the head to the firewall of the truck. Mine was corroded and literally crumbled apart when I grabbed it.

I replaced it with a battery cable I had lying around, I had to drill out the one connector end a lil bigger to go on the head stud, then I used my disc grinder to make a clean spot on the fire wall and used a self-tapping sheet metal screw and my drill to fasten the cable down. A good engine ground is essential to a properly running rig.
 
check crank sensor resistance cold-- if it's within spec, run it 'til it poops out and check again. It sounds as though you're losing the signal as it heats up and builds resistance.
 
Possibly a CPS. Next time it happens, unplug the connection at the back of the engine, drivers side. Key off, plug it back in. If it starts, the CPS is getting weak and can't read the flywheel - so, no spark.

Don't let your self spend more money on swapping parts if you can help it. A tow dolly can be cheaper sometimes than throwing money at it. I've towed my broke stuff and made out ok.

Check that CPS first up. They can be a pain to replace, mod one hole to slip over a bolt - and I've found I can get my small hand in there to do half the job, rather than lay under and use a long extension. It's right at the top of the bell housing, a strong light and magnets in the sockets keep from losing the bolts in there.
 
hmm..well about 3 weeks ago trying to get the alternator whine out of my subs, i ran 2 gauge power wire from: engine to battery,engine to firewall,battery to motor mount, so i doubt it ground but il go take a look over all of that again thanks for your opinion!
anybody else?
 
Possibly a CPS. Next time it happens, unplug the connection at the back of the engine, drivers side. Key off, plug it back in. If it starts, the CPS is getting weak and can't read the flywheel - so, no spark.

Don't let your self spend more money on swapping parts if you can help it. A tow dolly can be cheaper sometimes than throwing money at it. I've towed my broke stuff and made out ok.

Check that CPS first up. They can be a pain to replace, mod one hole to slip over a bolt - and I've found I can get my small hand in there to do half the job, rather than lay under and use a long extension. It's right at the top of the bell housing, a strong light and magnets in the sockets keep from losing the bolts in there.
hmmm il try that, ive also heard of heat soak destroying that sensor.

EDIT:the fuel pump is still cycling and working properly wouldnt the cps being bad not tell the pump/injectors to run corretly?
only cause when i pop that schrader valve its got pressure.
 
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Your motor needs 3 things to run:

1) Air - Im sure your getting air.
2) Fuel - Have you tested the pressure at the rail (Im pretty sure thats not your problem) You should be getting above 35psi. (maybe your fuel pump is getting hot after a while of driving and it takes a dump?)
3) Spark - Did your check your CPS? Im guessing thats what your problem is.
 
dealt with this on an 89 limited, would run and idle fine, then randomly just die, normally wouldnt start again untill then engine cooled to outside temp.

CPS was the fix. (its annoying to replace tho!)
 
dealt with this on an 89 limited, would run and idle fine, then randomly just die, normally wouldnt start again untill then engine cooled to outside temp.

CPS was the fix. (its annoying to replace tho!)

Its not so bad... All you need is a 11mm or 7/16" swivel socket and a long extension. (Preferably all in 1/4" drive) Shouldnt take long at all.
 
hmm..well about 3 weeks ago trying to get the alternator whine out of my subs, i ran 2 gauge power wire from: engine to battery,engine to firewall,battery to motor mount, so i doubt it ground but il go take a look over all of that again thanks for your opinion!
anybody else?
If you are drawing too much power or if you over lap something you could change the ohms or resistance of key wiring...its unlikely but should be considered. I'd unhook the system and see what happens
 
Sounds just like a bad CPS. My buddy's 88 did the exact same thing a few months ago. It would run just fine until it warmed up, then slowly shut down until it cooled back off again, to which it would fire right back up. New CPS and it was good to go.

Since you've got a Renix, should only cost you about $30-35 at your local auto parts store.
 
Sure sounds like a CPS, but I had a similar problem and it was the hot wire that goes from the positive battery clamp to the power distribution lug on the passenger fender. Not the large battery cable to the starter, the other, smaller (about 8 gauge) wire that provides all the other power to the Jeep. Mine would suddenly die, usually going around a corner. Turned out the corner put just enough lean on the engine to pull on this wire and open the circuit. Let it idle and go out and wiggle this wire (and all your grounds) aggressively to see if you can get it to quit. Cheap and easy test to at least eliminate them as the source before you go to more work and expense with the CPS.
 
Let it idle and go out and wiggle this wire (and all your grounds) aggressively to see if you can get it to quit. Cheap and easy test to at least eliminate them as the source before you go to more work and expense with the CPS.

this would give you something to do after you check the resistance (cold) for the CPS while you wait for it to warm up and poop out for the hot check and still wouldn't cost you any more "work or expense"
 
Don't forget the three grounds at the dipstick tube.

Sounds like the CPS--test it.
 
check crank sensor resistance cold--.............

Possibly a CPS................

Did your check your CPS? Im guessing thats what your problem is.


Sounds just like a bad CPS.

Sure sounds like a CPS,

Sounds like the CPS--test it.

Enough said.

why is it so easy to narrow it to CPS? because its the ONLY sensor on the renix that will keep it from running:wave:
 
replaced cps. it was able to run when i did it.
but. ive driven the farthest since the problem started.tonight i go a 45 mile venture to my old ladys with a friend of mine who lives out there following in his taco and a car dolly, hopefully il be pulling that dolly home tomorrow, and not riding in it!
 
Don't forget to give us a final word if its good--or not.
 
Next is the starter . . .

The CPS has to have a minimum cranking speed to pickup the signal. A weak, slow starter - not even at the grind along level - will keep the CPS from getting a useful signal.

But, since it started and ran, no problem.
 
well all seems well, its got a low rpm mis at speed, probaly just needs some timing and all around love before the trip, but it pulled the taco and dolly up some pretty bad hills(if your from norcal, i had to go through altamont and sunol grade/pass booo) held 55 alright so i guess its and i quote"the only sensor that renix cant run with out" after all.
 
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