90 Renix randomly dies

90 Renix manual tranny...


It is a testimonial to the Renix XJ engine system that I have not had any issues with it for years. Recently I noticed that my 5 year old exhaust manifold was cracked so when the Jeep died on the freeway and restarted after a couple of minutes and then died on me a couple of other times I figured I would replace the CPS and the manifold. Just did that using a "MOPAR" CPS from Morris. Note to self
(before doing that project be prepared to replace the fuel line o-rings.) When it died on the freeway I was not equipped to really troubleshoot I did crawl under rig and tapped on the fuel pump as a hail mary... After that it did start. Anyway still seeing the issue on my after work test drive. It seems to lose spark. Am thinking that it is not fuel related in that it just cuts out.. no coughing, no spluttering, no backfires.
Next step is to equip myself with a timing light, long jumper to hot wire the fuel pump, multimeter and starting fluid on board and just start driving it until it dies . Has anyone else seen this issue or similar? Figure I will start this thread and report back on my findings.

PS if you are ever stuck needing to fix the fuel line disconnects and don't want to wait for shipping you can get the o-rings at O'Reilly's part number
Dorman 800-013 at the ridiculous cost of $10 You need to mine out the old 0-rings and for feed and return use 2 o-rings with a little plastic spacer between them. If like me you cannot find the spacers you can use part number Dorman 46001 (emission hose) to make some new ones. Just slice the hose with a box cutter into 1/8" spacers and you will have a lifetime supply. (cost $5)

check the wiring to the cps. i toasted mine on the exhaust and it would short out and die.

90xj06 said:

check the wiring to the cps. i toasted mine on the exhaust and it would short out and die.

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We need to come up with a ceramic heat shield cover for them

The silicone cover that comes on them is good, but not good enough, and they seem to get loose too easy and run into the exhaust manifold....

Timing light on a Renix Jeep is useless, waste of money. The computer controls timing in real time. It is not adjustable.

Check out Cruiser54's guide on loss of spark, etc debugging on Renix rigs. Post up you test data here as you go along.

Check / replace plugs, plug wires, rotor and cap if they are old?

If you have starting problems check the cranking voltage of the CPS (disconnected) on the AC scale. Must be no less than 0.50 volts AC.

Check the sensor grounds to the battery (Cruiser54 guides) and battery connections. Renix is very sensitive to weak sensor grounds.

ICM and/or HV coil is also suspect for a no spark once the CPS, plugs and wires and cap and rotor are known to be good.

http://cruiser54.com/

lot's of good advice here, but did you start with the simple stuff like pulling and cleaning the battery terminals?
my 90 XJ gave me alot of trouble with occasional stalling, but mostly random momentary loss of power for a split-second, usually on bumpy terain like on a trail or wash-boarded road. drove me nuts on a 2 week trip out to Moab.
my negative battery clamp "appeared" perfectly clean and tight from above, but the under-side of it inside the post area was pitted and shorting.
sometime we over look the simplest things.

All helpful stuff and appreciated. However please assume that I will have covered the basics. Dual deep cycle batteries, ground straps up the ying yang, newish components all round. I am hoping to document my process in case it is useful for others. My intended question was "have you ever experienced an otherwise perfectly running rig cut out randomly with it not being the CPS? Agreed that the timing light is useless to "time" a Renix jeep but it sure beats a wet finger stuck in the plug boot troubleshooting on the edge of the freeway to assess spark. Guess a spark plug does it but then it is kind of hard to turn the key. I HATE intermittent faults.

It is not power from the battery
Pretty sure it is not the fuel pump or associated relays resistors etc.
starting never a problem


Will update when I get time to do further testing.

Actually appreciate the comment about battery terminal sometimes it is that simple.

Thanks Mike I never have had issues with the ICM or coil which makes them suspect

I wasted weeks on the same problem you have only to finally have the ICM croaked to a no start condition. Bottom of the sealed area was burned by then, the area that seals the circuit board on the ICM. Also the contacts on the HV Coil to the ICM get old and loose if you have not already cleaned and re-tensioned them.

Yep the only other no start I had was separation of the coil to the ICM. I um hit it with a pipe and it's been working ever since. And that was 3 years ago

Do Tips 1,3,4, and 5 just cuz.

CPS can be tested.

My recent no starts onmy 89 have been at the ECU harness as it makes the tight bend to plug in.
I unbolted the ECU and let it hang by one screw and it fires right up and never ran better

Want to thanks Cruiser54 for all his work. Brilliant list. Have not had a repeat of the problem yet but am going through the list. Of course finding things that I had thought sorted but not. Am definitely planning on doing some of the ground improvement bits. Merry Christmas

nickguy said:

Want to thanks Cruiser54 for all his work. Brilliant list. Have not had a repeat of the problem yet but am going through the list. Of course finding things that I had thought sorted but not. Am definitely planning on doing some of the ground improvement bits. Merry Christmas

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Merry Christmas. You made my day.

Redid grounds to Dipstick... pretty atrocious state.
Refreshed Coil/ICM connections... Some corrosion on coil terminals.. Cleaned and replaced.

Plug wires nearly new and really clean.. While looking at the distributor/rotor arm/cap I decided that 250k miles is about enough. Am going to replace the dizzy with a new/reman crown unit and keep the original as a spare.

Generally when this rig dies I will get another 90 Renix so am ok with refreshing parts.

Problem still has not returned. It did happen in very cold temperatures (10* f) Am wondering if I had some icing in my gas... Throwing in some alcohol for good measure. It is a good reason to go through the FI system again though so guess I am glad it happened.

nickguy said:

Redid grounds to Dipstick... pretty atrocious state.
Refreshed Coil/ICM connections... Some corrosion on coil terminals.. Cleaned and replaced.

Plug wires nearly new and really clean.. While looking at the distributor/rotor arm/cap I decided that 250k miles is about enough. Am going to replace the dizzy with a new/reman crown unit and keep the original as a spare.

Generally when this rig dies I will get another 90 Renix so am ok with refreshing parts.

Problem still has not returned. It did happen in very cold temperatures (10* f) Am wondering if I had some icing in my gas... Throwing in some alcohol for good measure. It is a good reason to go through the FI system again though so guess I am glad it happened.

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Ya done good.

So there are times that I have faith in humanity. This is not one of those times. Noticed on install that the I could turn the rotor arm independent of the shaft. Crown had shipped the distributor minus the plastic coupling that ties the hall effect sensor to the rotor. I suspect that someone just mined this component from the distributor and returned it to them for a free fix. What, as we say in the UK, a wanker. Way to stick it to the man!

nickguy said:

So there are times that I have faith in humanity. This is not one of those times. Noticed on install that the I could turn the rotor arm independent of the shaft. Crown had shipped the distributor minus the plastic coupling that ties the hall effect sensor to the rotor. I suspect that someone just mined this component from the distributor and returned it to them for a free fix. What, as we say in the UK, a wanker. Way to stick it to the man!

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May the fleas of a thousand camels infest his groin area.....

Well perhaps it is me who deserves to be fleabitten and serves me right for posting from the hip. Looking at it more closely the Crown dizzy uses a steel spacer between the stator and the pulse ring mount which is actually an improvement on the factory plastic spacer. It looks like the idea is that when the distributor is assembled that the pulse ring mount is pressed on to the shaft. With the one they sent me the tolerances must be way off because it is loose. Guess I could tack weld it in place but then what is the point of buying a new dizzy? and figuring out the clocking would be a pain. Made in China. Think I will return in and rebuild a junkyard dizzy.