No start, no spark, no CPS?.... Please help - Jeep Wrangler Forum
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Old 03-20-2019, 08:02 AM
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No start, no spark, no CPS?.... Please help

Hi Everyone, long story so please bear with me.
I bought an 89 YJ back in July. The original 4.2L engine had been swapped out with a 91 4.0L (Jasper) engine by the PO. The seller told me the jeep needed a new exhaust and had no other issues. It started right up, clutch felt good, it drove well, so I paid the money and drove it home (about 40 min drive to my house) with no issues other than a strong exhaust smell. I drove it a few times around the neighborhood and did a basic tune up (oil change, new spark plugs, spark plug wires, rotor, distributor cap, replaced several fuses). Replaced the exhaust too. Over the summer, I ran into a soggy clutch pedal and added replacement clutch kit (master/slave/clutch plate) to my “to do list”. I was able to get the clutch peddle primed and would drive the jeep locally on occasion, no more than 5 mins from home, so I decided to hold off on the clutch kit project. In September, I took it out and I was driving it when it backfired (sounded like a gunshot). When that happened, the jeep wouldn’t accelerate above 20 mph and it was smoking badly out of the exhaust. I pulled over and AAA towed me home. Once it was home it would start up and run (smoke from the exhaust) and then die after about 20 seconds of idling. After a few days of failed starts, I was no longer hearing the inline electric fuel pump when I tried to start the jeep. A buddy said it sounded like the jeep was starving for fuel so I replaced the fuel pump. Even after the fuel pump replacement the jeep would occasionally start and would die after 20 seconds. Just a side note, the jeep cranked and still cranks strong – I believe the battery is good.
Since September I have been troubleshooting the ongoing start issue and I decided to perform the clutch work. After replacing the clutch, I tried to start it and it did start a few times, but died each time after 20 seconds. While trying to troubleshoot I realized i was no longer getting spark.
I have been on a ghost hunt since and replaced the coil, the pcm, the ASD Relay, checked my grounds (I think all of them), charged my battery (several times), redid the battery terminal connections, replaced the ignition switch and no change. I am still not getting a spark.
A few notes, the 89 4.2L engines did not have a CPS (from what I’ve read) and the 4.0L engine (currently in my jeep) does not have a CPS (but it still drove before it went to hell). I don’t even have the wires to install a CPS if I wanted (PO cut a bunch of wires inside the harness). I have 12V power from the battery to the coil and power to the ASD, but no power coming from the ASD (to the solenoid, fuel pump, etc). Also when i crank the engine, power from the battery to the coil drops to about 3-4 V . The radio, headlights, dash lights all work with the key in the "on position" and most of the time the wiper spray, horn, and heater work. When I was able to get the jeep to run, I noticed that the new fuel pump came on at startup, but the heater would not turn on and the horn would not sound. After the jeep shut off, I tried to turn the jeep over, the jeep would not run, the fuel pump did not come on, but the heater and horn worked. I am out of ideas and looking for some help. Sorry if this sounds confusing. Any thoughts/suggestions?

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Old 03-20-2019, 11:31 AM   #2
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Welcome to the Forum mikejunker89,

Someone here should be able to help you out.

Good Luck, L.M.

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HEI distributor with computer and all related relays and wiring removed.
12K Badlands winch with dual batteries.
Warn front bumper. Matching imitation Warn bumper on the rear.
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Old 03-20-2019, 11:52 AM   #3
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Take out and check the fuse box connections in front of the battery tray. Literally take it out and check underneath the ASD / FP / IGN relays for any pins or connectors that may have broken or pulled out of the sockets. I had a real bugger of a problem Fuel-Pump related a few years ago and it was a 20 second fix after I checked those connections. Reason I'm suggesting this is because you said you have power going in but not out. Don't over-bend the wire harness loom just get the fuse-tray up far enough to were you can see the terminals and check for continuity.
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Old 03-20-2019, 12:46 PM   #4
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i dont believe there is a fuse box in front of the battery tray, but i will check tonight. i know i have 2 relay switches there, but not sure about fuses.
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Old 03-20-2019, 12:46 PM   #5
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Old 03-20-2019, 01:15 PM   #6
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OPs Wrangler is a 1989 model. I think the PDC (power distribution center) started with the 1990 model.

The ignition switch is an electrical switch at the bottom of the steering column. It's controlled by a rod running down from the key cylinder.
Find a post by Got It At Last and look in his signature for a link to several factory Service Manuals. In the FSM that is closest to your Jeep, find the ignition circuit schematic. You're going to have to be creative in your interpretation of the schematic since the PO has cut away some of the 4.2 wiring. Most likely the wires that were cut away were to the 4.2 carbureted emission controls.
Make sure that there is power to the switch and power exiting the switch with the key on.

Good Luck, L.M.
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"Wrangler....It's not just a vehicle, It's a lifestyle".
.................................................. ........................
1987 YJ-4.2L-Standard Shift- Re-manufactured Carter Carb-2" body Lift-31X10.5X15 BFG KOs-190K Miles No back seat.
HEI distributor with computer and all related relays and wiring removed.
12K Badlands winch with dual batteries.
Warn front bumper. Matching imitation Warn bumper on the rear.
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Old 03-20-2019, 01:42 PM   #7
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x2 above,.... with intermittent horn and wiper issues I'd check all the connections there, All your ignition loops through that harness, Pull apart your plugs clean the connections with an emery board or sandpaper, touch a dab of di-electric grease or equivalent. Also hit both sides of your intermittent wiper control also.
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FSM Manuals https://www.dropbox.com/sh/0vfmk6jc5...v7lceZk7a?dl=0
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Old 04-15-2019, 05:40 PM   #8
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i am sorry, i have no clue how to check for power in and out of the ignition switch. i removed the bolts to the steering column and have minimal access to the ignition switch (that thing is hard as hell to get to). what i do know is that when i turn the key to the on position, the horn, radio, heat, etc. comes on. The jeep will crank all day too. I have no power running to the starter relay though (regardless of if the key is the on or off position). The battery is fully charged and i have 12 v running from the positive terminal to the "F" (fuel on the starter relay) and the "Batt" post on the starter relay. i also have 12v from the positive battery terminal to the starter.
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Old 04-17-2019, 08:43 AM   #9
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Might be bad capacitors on the ECM. Not too hard to swap out if you have soldering skills. Usually diagnosed when no check engine light is displayed when you turn the key to the on position.
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Old 04-17-2019, 10:27 AM   #10
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Welcome to the Forum dzldude,

Good Luck, L.M.
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Old 04-22-2019, 04:46 PM   #11
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Just a brief update. i was able to find an awesome write up on this site which gave me a step by step diagnostic process. I was able to verify the ignition switch has power in and out. i also checked the ecm pins (3, 9, 11, and 12). they all checked out good as well. so after going through the entire write up i was leaning towards the ecm. so i went out and got new capacitors and was able to replace the capacitors. i plugged the ecm back in and..... nothing. still no spark, strong crank. i knew it right away it wasnt going to work because i didnt hear the fuel pump come on when i turned the key to the on position. well i'm out of ideas.

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