i literally just joined Cherokee Forum five minutes ago in hopes of trying to solve my everlasting dilemma..

a little over a month ago, i purchased a 1990 cherokee laredo knowing it was going to be a bit of a fixer (new windshield, tune up, lift, etc.) - nothing major. just something i can have and build as my very own seeing my last jeep didn't work out as planned (those 2.8s... )

when i first went and looked at it, the lady told me it needed a new cps.. fair enough, i've dealt with that before. i put a new one in and she started right up. when i went to bring the heap home, it decided it was going to not run... literally five minutes after the title was in my hand. when i got her home, she wasn't getting spark as well as fuel pressure, now i've got it to where shes got pressure, but no spark.

i have replaced the coil, distributor, fuel filter, gas, tested the ballast resistor - it's good. checked and replaced any and all fuses, new battery, cam sensor is fine, checked for any grounds, can't find anything wrong with wiring, oh and i've replaced the CPS three times now. two from Napa, and the last one from Carquest.

still no spark. its just continuously cranking. honestly, i'm to the point of just selling it, and attempting to start fresh once again. HELP!?

Did you replace/check rotor and spark plug wires?

Hi had the same problem with my nephews truck, . Turned out to be the pick up in the dist.?? Put a new one in and fired right up.. good luck..

Is it cranking at normal speed or slower than normal? IIRC Renix needs to see a certain rpm before it fires the plugs.
Is there power to the coil?
How about the negative side of the coil connector, should switch to ground every time a plug should fire. A test light between the coil negative and ground should flash. If it stays lit while cranking (no flash), check the harness to the PCM.

Check all your fuses and releys, I know ur PCM will cut ur spark if something is wrong, my PCM cut mine when my fuel pump fuse blew

The distributor on a 90 can be unplugged and it will still run. Different system than yours.

Has an ECu, not PCM, and it is not fused.

TEST the CPS first. Here's how:


Renix CPS Testing and Adjusting
　
　
Renix CPSs have to put out a strong enough signal to the ECU so that it will provide spark.
Most tests for the CPS suggest checking it for an ohms value. This is unreliable and can cause some wasted time and aggravation in your diagnosis of a no-start issue as the CPS will test good when in fact it is bad.
The problem with the ohms test is you can have the correct amount of resistance through the CPS but it isn’t generating enough voltage to trigger the ECU to provide spark.
Unplug the harness connector from the CPS. Using your voltmeter set on AC volts and probing both wires in the connector going to the CPS, crank the engine over. It won’t start with the CPS disconnected.
You should get a reading of .5 AC volts.
If you are down in the .35 AC volts range or lower on your meter reading, you can have intermittent crank/no-start conditions from your Renix Jeep. Some NEW CPSs (from the big box parts stores) have registered only .2 AC volts while reading the proper resistance!! That’s a definite no-start condition. Best to buy your CPS from Napa or the dealer.
Sometimes on a manual transmission equipped Renix Jeep there is an accumulation of debris on the tip of the CPS. It’s worn off clutch material and since the CPS is a magnet, the metal sticks to the tip of the CPS causing a reduced voltage signal. You MAY get by with cleaning the tip of the CPS off.
A little trick for increasing the output of your CPS is to drill out the upper mounting hole to 3/8" from the stock 5/16", or slot it so the CPS bracket rests on the bell housing when pushed down. Then, when mounting it, hold the CPS down as close to the flywheel as you can while tightening the bolts.

　
　
Revised 01-26-2013


How is the wiring for the CPS routed? Getting against teh exhaust manifold?

Click on the link in my signature. It's PINK.

Do the things in posts #1, 3 and 4.