Topic: Help Me: 96 Cherokee won't start

My winter beater is beating me.

Car is a '96 Cherokee, 4.0, 4x4, 5spd with 280k. I bought the Jeep 22k ago at which point in time it was having some issues that the PO and I both worked on. At that point it would not rev over 3000rpm. Felt like a soft rev-limit. He replaced the computer, MAP, TPS, IAT, IAC, plugs, wires, rotor, cap and coil. When I got it I replaced the CAS which then let it rev slightly higher, to 4000rpm. About 2000miles into ownership it started breaking up and stuttering on the interstate. It felt like ignition so I replaced the coil. Not another issue for 19000 miles. Over this past summer I replaced the fuel filter preemptively and put in a new CPS hoping to get full rev range. Still only revs to 4000rpm.

Last week I was driving to work and it stuttered and coughed again. I thought the coil was the culprit because that fixed a similar issue last time. The new coil did not fix the problem. Then I thought maybe the original fuel pump was going so I replaced that. No dice. That lead me to thinking it was CPS as it felt like ignition cut and my tach was doing weird things. Today after limping the Jeep home from buying the CPS I brought the car inside to do an oil change and CPS replacement. After the oil change the car wouldn't start. I put the new CPS in and it fired right up, for about the 10 feet to get out of the garage and died. I couldn't get it to restart so I used the starter to drive it into my parking spot, where it now sits.

I am perplexed as to what I should do next. I know I need to test for fuel and spark. I checked that I have fuel pressure at the rail, so I'm guessing I still have spark troubles. Not sure what to check next.

Planet Express
"IOE" "C Win" 4834.701 Race Miles and counting
Toyocedes
"Least Southern Pickup Truck" "IOE" "C win" "C win (again?)"

Re: Help Me: 96 Cherokee won't start

Hand trace the CPS harness for bare spots yet?

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Re: Help Me: 96 Cherokee won't start

Not yet. It's like 20° and windy so I don't want to do too much outdoors right now. But it does sound like straight up CPS right?

Planet Express
"IOE" "C Win" 4834.701 Race Miles and counting
Toyocedes
"Least Southern Pickup Truck" "IOE" "C win" "C win (again?)"

4 (edited by Team Infinniti 2019-01-01 09:12 PM)

Re: Help Me: 96 Cherokee won't start

Not exactly like I have seen before.

Got codes?

Homestead Chump 5th-Sebring 6th-PBIR Lemons 9th - Charlotte Chump  CrashnBurn 9th
Sebring 6th again -NOLA Chump 1st -PBIR Chump Trans Fail 16th
Daytona 11th - Sebring 6th - Atlanta Motor Speedway 2nd - Road Atlanta Trans Fail 61st-Road Atlanta 5th
Daytona 13th - Charlotte 9th - Sebring 2nd-Charlotte 25th broken brakes - Road Atlanta 14 10th-Daytona 14  58th- Humid TT 19th Judges' Choice!

Re: Help Me: 96 Cherokee won't start

FPRbuzz wrote:

Not yet. It's like 20° and windy so I don't want to do too much outdoors right now. But it does sound like straight up CPS right?

So this is an older issue but there is a chance you got some new old stock so...

There was a period about 4-5 years ago where Jeep and Volvo (red block) among others got a batch of CPS's with extremely early failure rates.  As in anecdotally about 30% of them were failing in under 500 miles.  It got to the point the Jeep guys that actually went out in the boonies with their rigs were adopting the process old Volvo guys had used for a while...install, run for 1000 miles then uninstalled and put in the glove box as a know good spare. (Every old red block guy has MAF, ignition amplifier, CPS and jumper wires for the fuel pump relay in their supplies).

Re: Help Me: 96 Cherokee won't start

I left my reader at home(45 hours from here) so I don't have codes yet.

I've heard about the bad CPS issue. I would hope that even the bad ones last longer than 10' of driving, but maybe not.

If it warms up today I'm going to go look at the dizzy side of things and attack everything with a multimeter.

Planet Express
"IOE" "C Win" 4834.701 Race Miles and counting
Toyocedes
"Least Southern Pickup Truck" "IOE" "C win" "C win (again?)"

Re: Help Me: 96 Cherokee won't start

I worked from the spark plugs back today. No spark at the plugs, dizzy wire has good continuity, 12v to the coil but no trigger signal to the coil. This tells me:


New CPS was a crib death, but the test procedure says it's good

PCM is bad

Some wiring somewhere is bad

Planet Express
"IOE" "C Win" 4834.701 Race Miles and counting
Toyocedes
"Least Southern Pickup Truck" "IOE" "C win" "C win (again?)"

Re: Help Me: 96 Cherokee won't start

Wriggle PCM connectors, if it starts, bad pcm

Homestead Chump 5th-Sebring 6th-PBIR Lemons 9th - Charlotte Chump  CrashnBurn 9th
Sebring 6th again -NOLA Chump 1st -PBIR Chump Trans Fail 16th
Daytona 11th - Sebring 6th - Atlanta Motor Speedway 2nd - Road Atlanta Trans Fail 61st-Road Atlanta 5th
Daytona 13th - Charlotte 9th - Sebring 2nd-Charlotte 25th broken brakes - Road Atlanta 14 10th-Daytona 14  58th- Humid TT 19th Judges' Choice!