klaichkr Posted February 11, 2020 Share Posted February 11, 2020 So yesterday I bought my first comanche. It's an 87 with a automatic transmission and 107,000 miles. Drove great during the test drive and previous owner stated they never had any problems with it. On my 1 1/2 hour drive home going up a hill I pushed the power transmission switch and the jeep shifted down and after a couple seconds quit firing. Motor turns over fine just won't fire. Had to get it towed home. I am getting fuel and spark and the timing seems to be in the right place just from going to tdc on 1st cylinder and looking at distributor. Not sure if it's related but I am reading 3 volts at all the terminals on the fuse panel. I am taking Wednesday off to try to get it figured out so any advice is greatly appreciated. Getting full 12-13 volts at the radio and cigarette lighter. Link to comment Share on other sites More sharing options...
1989commanche Posted February 11, 2020 Share Posted February 11, 2020 I would start at the battery terminals and grounds first. Shine them up and see if it improves. Sometimes that’s all it takes. Link to comment Share on other sites More sharing options...
fiatslug87 Posted February 11, 2020 Share Posted February 11, 2020 Do as suggested above but also check voltage at the battery, if low charge the battery then check voltage at the battery while the engine is running, should be around 14.5 volts if not your alternator is bad. Also add your truck specs to your signature. Link to comment Share on other sites More sharing options...
Eagle Posted February 11, 2020 Share Posted February 11, 2020 17 hours ago, klaichkr said: ... I am reading 3 volts at all the terminals on the fuse panel. ... Getting full 12-13 volts at the radio and cigarette lighter. The radio and cigarette lighter are fed from the fuse panel. How are you getting 12 volts at the radio and cigarette lighter if all the terminals on the fuse panel only show 3 volts? Link to comment Share on other sites More sharing options...
klaichkr Posted February 11, 2020 Author Share Posted February 11, 2020 I'll have to look when I get home, tested 4 or 5 on fuse panel and got 3v. May not have checked the radio. Was late and dark so called it a night. Link to comment Share on other sites More sharing options...
Gouda Posted February 12, 2020 Share Posted February 12, 2020 I had an issue where I was getting very low voltage at certain fuses awhile back. I would suggest getting down in there and checking your teminals for corrosion and cracking. I had one that was very obviously breaking apart and when I pulled the panel apart I found that virtually all of them were coming apart to some degree. Even the terminals that looked fine began coming apart when I poked at them. Link to comment Share on other sites More sharing options...
Eagle Posted February 12, 2020 Share Posted February 12, 2020 2 hours ago, klaichkr said: I'll have to look when I get home, tested 4 or 5 on fuse panel and got 3v. May not have checked the radio. Was late and dark so called it a night. You wrote that you read 3 volts on "all the terminals." I don't mean to bust on you, but we're all willing to help as much as we can. Remote diagnosis is difficult enough with accurate information. When you say you tested "all the terminals," we have to proceed on the belief that you tested ALL the terminals. You don't help yourself by extrapolating and generalizing. Thus endeth the sermon for today. Link to comment Share on other sites More sharing options...
klaichkr Posted February 12, 2020 Author Share Posted February 12, 2020 Okay, sorry for not being more specific. When I checked last night everything I checked was 3v but when I checked the radio and cigarette lighter they were 12v. Tonight they are all 12v with exception to the dash lights which only read 1v but that is visibly corroded, not sure what changed between then and now. Will clean all grounds tomorrow and see where I'm at from there. Thanks for all the suggestions. Wondering what the odds are the timing chain may have skipped a bit when it shifted down into power mode causing it not to run? Link to comment Share on other sites More sharing options...
Jeep Driver Posted February 12, 2020 Share Posted February 12, 2020 7 minutes ago, klaichkr said: Wondering what the odds are the timing chain may have skipped a bit when it shifted down into power mode causing it not to run? 0 Link to comment Share on other sites More sharing options...
Eagle Posted February 12, 2020 Share Posted February 12, 2020 48 minutes ago, klaichkr said: Wondering what the odds are the timing chain may have skipped a bit when it shifted down into power mode causing it not to run? As Jeep Driver said -- zero. I came to Jeep from AMC. On the late 60's AMC V8s, the timing gear set used nylon teeth on the cam sprocket, and they had a tendency to jump time between 150,000 and 200,000 miles. Thinking that the 4.0L used the same setup, when my original '88 XJ reached 150,000 I started thinking I was living on borrowed time, so I bought a new timing set. Hmmm ... it wasn't a flat chain, like in the V8s, it was a roller (or "roller-like") chain, and the cam sprocket was all steel. But I had to be sure, so I opened up the timing chain cover. Sure enough, the factory sprocket was steel and the chain was the roller-type chain. And it wasn't stretched even a little bit. I had it open at that point so the new parts went in, but it was actually watsed time and money. It didn't need to be replaced. Link to comment Share on other sites More sharing options...
klaichkr Posted February 12, 2020 Author Share Posted February 12, 2020 Thanks again, will clean all grounds and start from there on getting it up and running again. Link to comment Share on other sites More sharing options...
klaichkr Posted February 13, 2020 Author Share Posted February 13, 2020 Okay, today I went through the grounds and have 12v at all fuse terminals now. I can hear the fuel pump prime when I turn the key over and have 12v to the coil but don't have spark. I tested the cps and it was only at 2v when cranking so I picked up another (off brand). This one tested at 3v and i read on this forum it should be at 5v so I went and got another (duralast from autozone) It still only reads 3v when cranking. I am using a cheap harbor freight multi meter so not sure how accurate the readings are. Should I try another cps or start looking somewhere else? Link to comment Share on other sites More sharing options...
Jeep Driver Posted February 13, 2020 Share Posted February 13, 2020 1 hour ago, klaichkr said: Okay, today I went through the grounds and have 12v at all fuse terminals now. I can hear the fuel pump prime when I turn the key over and have 12v to the coil but don't have spark. I tested the cps and it was only at 2v when cranking so I picked up another (off brand). This one tested at 3v and i read on this forum it should be at 5v so I went and got another (duralast from autozone) It still only reads 3v when cranking. I am using a cheap harbor freight multi meter so not sure how accurate the readings are. Should I try another cps or start looking somewhere else? It does not fire at all? No spark? May be a bad coil. Link to comment Share on other sites More sharing options...
klaichkr Posted February 13, 2020 Author Share Posted February 13, 2020 I put the factory cps back in after checking with an ohm meter and it being at 165. I believe factory spec is 200 +-75. Now have spark but am pretty sure the timing is off. I watched a video where the alignment roll pin on the camshaft sprocket broke and it wasn't aligned properly. I'm wondering if this is what happened when i pushed the power trans switch and it downshifted. It was only a second or two after shifting it died. Link to comment Share on other sites More sharing options...
klaichkr Posted February 13, 2020 Author Share Posted February 13, 2020 This is where the distributor is at #1 tdc comanche dist.jfif Link to comment Share on other sites More sharing options...
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