Wont Start After Mud/Water

Hello everyone, Long time lurker first time poster!
I have a 1988 Jeep xj, 6.5 lift and 35s, and i have been having electrical problems for alittle while now, but nothing like this! It started with a blower motor not turning off, then lights not turning on(fixed with new fusible link). The only motifications done(as far as im aware of ofcoarse) is i squeezed an 800cca 34 series battery in.
Well to the point, i was mudding last weekend, hit a pretty big puddle/mud hole, and it just shut down on me and wont start again. This has happened once before after a big rain storm, but after sitting out for a day it started again, so i never thought anything of it. But this time, it wont restart. I replaced CPS sensor, ignition coil and map sensor.. all with no luck. I sprayed started fluid in the throttle body, still no luck. I did clean my TPS and idle control valve as well as the c101 bulk connector about a month back.
Any advice on what i should look at now? Ive done some searching, and still no luck. Im debating if i should do a c101 eliminator, but being new to a 1988 im not sure where to even look as far as wiring when it comes to this. Any help is good help! I really appreciate it!
Thanks,
Adam

The first place I always look is inside the distributor for water, then I check for spark. Could be many things but this is the most common.

Then I pull the plug cables out of the distributor cap and clean the boots out with Q tips. The same with the boots at the plugs.

Also look inside your air cleaner and make sure the filter element is soaked in water. If it is water logged it can shut off the air to the motor.

If this all checks out get back to me and we can check some more stuff.

When you turn the key to run you need battery voltage to the larger yellow wire running to the ignition module under the coil.

The next thing to do is to start separating connectors and cleaning them out, water gets in there. Most are water resistant, none are water proof. Be really careful with the connectors, they get old and brittle and break easily.

8mud- I checked the distributer for water, and there def was. So i cleaned it all out, changed rotor and cap.. put it all back and still no fire. I check the bigger of the yellow wires, its getting voltage. Im still checking all there connectors for water, so far im cleaning the c101 as we speak.
Im almost wondering if the engine is flood preventing me from starting it. I also didnt completly take apart the distributer, i took the cap and rotor off and spray electric cleaner in there and wiped down what i could see.

Water can hide in the distributor under the sync sensor plate, you need to blow it out.

Pull a spark plug (or use an old one) open it up to around .060, hold it against a good ground and have someone turn the motor over. You should get a nice thin sharp blue/whit spark. A thick and yellow spark or a yellow spark that kind of splashes or no spark, isn't good. Be careful, rubber gloves are plus, a good ground is a must and whatever you do, don't press your crotch against the fender while your checking the spark.

While you have the plug out look in the hole with a flashlight and see if it looks wet in there.

Pull the rubber top off the TB and check the rubber for water, it gets caught between the ribs. Dry your filter off, vacuum cleaner or compressed air.

If your spark and air is good the only thing left is fuel.

Check the simple and obvious stuff first, then move on to the more complex. You never know you may screw something up worse than it is and still not find the main problem.

It's also a good idea to check that something is coming out of the exhaust pipe as you crank the motor over. Muddy water can get into the muffler or cat and turn to clay and then stone, when it dries.

I've been in up to my windshield before. It's fun while it's happening but cleanup is a pain.

You have said that it is not starting, but have not confirmed yet if it cranks over. We are assuming it cranks over, just doesn't start, correct?

The base underneath the coil is also a possibility. If you remove the coil, unplug the two connectors that plug into the base and remove the base, look at the bottom of it. The bottom is filled with an epoxy-type material. If this material shows ANY cracks at all, moisture can get in there and short it out, making it unable to start. I forget what that part is called (ignition coil base, or something like that), but it is readily available at parts stores.

Silly question, did you check your fuses? I had a short on my 02 sensor this past weekend that blew my 30 amp fuse. The engine would crank, but never fire. My Jeep is a 96, so it may be different.

hey guys, i tried it all... still no luck, i checked the voltage on all sensors, still nothing. No spark.
Now i know on Renix jeeps, the odds are against this, but could it possible be the pcm being bad? im trying to sell it, so i dont want to throw money at it just to "test"

Andy in Pa. said:

The base underneath the coil is also a possibility. If you remove the coil, unplug the two connectors that plug into the base and remove the base, look at the bottom of it. The bottom is filled with an epoxy-type material. If this material shows ANY cracks at all, moisture can get in there and short it out, making it unable to start. I forget what that part is called (ignition coil base, or something like that), but it is readily available at parts stores.

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It's called the "ignition control module" (located below the coil) and it could be in play for no-spark.

birchlakeXJ said:

It's called the "ignition control module" (located below the coil) and it could be in play for no-spark.

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yes sir, i work at advance auto, and i was able to find it on my computers, i just put an order in for one day. I am crossing my fingers, because i am shortly running out of ideas haha

no spark? have you spiked the cps? if you spike it and it starts its a bad cps.

DesertRunner said:

no spark? have you spiked the cps? if you spike it and it starts its a bad cps.

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would you mind explaining what you mean by spiking the cps? thanks

Hey yall, i tested the CPS from my job that installed.. .1 ac volts(i guess its supposed to be .35 or higher, wonderful, that may have something to do with it haha

pbfreak9999 said:

Hey yall, i tested the CPS from my job that installed.. .1 ac volts(i guess its supposed to be .35 or higher, wonderful, that may have something to do with it haha

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I buy only Mopar crank sensors from Jeep. Aftermarket crank sensors are very "hit and miss" with a lot of miss....

pbfreak9999 said:

Hey yall, i tested the CPS from my job that installed.. .1 ac volts(i guess its supposed to be .35 or higher, wonderful, that may have something to do with it haha

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Needs to be 0.50 AC Volts while cranking, minimum

Also you need to drill out the bolt holes one drill size number larger, and push the CPS closer to the Flex plate - flywheel while tightening the bolts.

Use only a deal CPS, or a Standard Auto CPS from Rock Auto (Made in Italy, and NOT made in CHINA).

Hey everyone, I just wanted to say thank you for everyone who's helped me threw this! After getting a mopar crank sensor(gettin .5 ac volts) new coil, ignition module, distributor, knock sensor, and I did a c101 connecter eliminator, I found out it was the computer. Me and my buddy found burn marks on the board of the computer. I put a reman pre programmed cardone computer in from advance auto. Boom, spark again.. I do plan on putting in an inline fuse to the computer just in case lol.
Once again, thanks to all whom helped!
Adam

If you are not going to keep the old ECU, 5-90 will want it!!

Ecomike said:

If you are not going to keep the old ECU, 5-90 will want it!!

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chances are that the Cardone reman. unit has a core charge associated with it-- he might want to work a trade with Jon for one that he's already played with.

May I ask what you'd like to do with my old burnt unit?(Out of curiosity) Yes, I need an old one for a core charge.

Jon, AKA 5-90 is working on figuring out what makes Renix ECUs tick, reverse engineering, code and hardware in his spare time.

Ignition Module with organics in the mud, CPS will sometime get mud in the port and/or faulty O2 Sensor connection causing it to malfunction, happened to me one night right in the middle of a mud hole on FR-572 ONF and then got strapped/towed back to O-Town by a KJ…………

If you want the best possible solution get ride of the Renix EFI system, because trying to remap this systems ECU takes many hours, and if one does not have the scanner & SEMI it’s near impossible. By the way JD and I did that back in 2002 when we bought the AMC’s Scanner & SEMI Wire at a Jeep Dealer Ship’s put Out of Business auction. My suggestion would be to find a 96 to early 98 w/ Distributer or a 98.5 and later with coil packs OBD II production Engine Harness & ECU, I just pulled my 4.6L AMC because the Renix Engine Harness gave out and replacing it with a remanufactured and/or used OE engine harness was a no even if I could find one…………