CallmeMaybe Posted November 27, 2012 Share Posted November 27, 2012 For those of you who don't know the story I picked my MJ up last Sunday not running. Ive since seated the rocker arms, new alternator and juiced the battery. But its still not firing up. When I went to pick it up we jumped it for a sec and it ran for about a min then died. I figured the seller didnt tighten the rockers correctly after his headgasket replace and the vehicle wasent getting the right air/fuel ratio and was dying. So that being said why isnt it starting now? Link to comment Share on other sites More sharing options...
flint54 Posted November 28, 2012 Share Posted November 28, 2012 Do not recall the other thread, but a few basic questions please to refresh us: 1) Does it crank, i.e., turn over readily with the starter? 2) Have you measured the fuel pressure and the fuel flow rate at the rail? 3) Have you checked for spark at each plug wire? 4) Have you tried a shot of starter fluid into the air intake? 5) What do the plugs look like? 6) What are the compression values? Link to comment Share on other sites More sharing options...
CallmeMaybe Posted November 29, 2012 Author Share Posted November 29, 2012 Update, got no spark at the plugs. Changed distributor, plugs, and wires. Still no spark. Thinking Coil, what do you guys think? Link to comment Share on other sites More sharing options...
Biotex Posted November 29, 2012 Share Posted November 29, 2012 In my experience, the coils don't usually become intermittent. Now the ignition module will run for a couple of minutes then shut down. Not saying it isn't the coil, but I would have the module tested first. It's an 88? Link to comment Share on other sites More sharing options...
CallmeMaybe Posted November 29, 2012 Author Share Posted November 29, 2012 http://www.autozone.com/autozone/parts/Duralast-Ignition-Control-Module/1988-Jeep-Comanche-4WD/_/N-iugb2Z9n80t?itemIdentifier=94348_300759_0_ If thats what your talking about Ive just pulled it and going to get it tested tomorrow. Its 3 ports but mine only had 2 connectors... normal? Link to comment Share on other sites More sharing options...
CallmeMaybe Posted November 30, 2012 Author Share Posted November 30, 2012 So I got the module checked at the parts store and it passed twice. Figured I had a bad coil. Bought a new coil and still have no spark from the coil to the distributor. Any ideas? Link to comment Share on other sites More sharing options...
CallmeMaybe Posted November 30, 2012 Author Share Posted November 30, 2012 Yes its a '88 Link to comment Share on other sites More sharing options...
gogmorgo Posted November 30, 2012 Share Posted November 30, 2012 Is there power going to the coil? Figure out where the spark "stops" and go from there. I had an intermittent no-start (more like an intermittent start...) in a GM HEI, threw distributor parts at it for about a year. Every time I tested for voltage somewhere or swapped something out, it would work for a day or two (got three weeks out of pulling the whole thing apart for a new pick-up coil). Once I gave up and threw a new dizzy in, the issue was gone. And I almost immediately discovered where a wire was shorting out against the case of the old one. Whenever I did something, I bumped the wires slightly, disrupting the short until the wire went back to where it wanted to be. A strategically placed one-inch strip of electrical tape would have saved me lots of $$ and grief... Moral of story, check for shorts. Link to comment Share on other sites More sharing options...
CallmeMaybe Posted November 30, 2012 Author Share Posted November 30, 2012 I don't see how it can't be some wiring somewhere. Gonna check everything next. Link to comment Share on other sites More sharing options...
MJCARENA Posted November 30, 2012 Share Posted November 30, 2012 I would check the crank position sensor first. Try disconnecting it and reconnect it first. The if it still won't start check it out with a meter.CRUISER54 has posted a write up how to do this. Do a search on it. I would, but on my phone. Link to comment Share on other sites More sharing options...
cruiser54 Posted November 30, 2012 Share Posted November 30, 2012 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, 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 07-30-2012 Link to comment Share on other sites More sharing options...
Biotex Posted November 30, 2012 Share Posted November 30, 2012 If it turns out to not be the CPS, then the next in line would be the reluctor inside the distributor. They are pretty rliable, but do cause troubleshooting nitemares. Thankfully they are really inexpensive, so may want to just go ahead and swap it out for a new one. You really do need to verify you have voltage to the ignition components first. It could just be a simple break in a 12v wire. Link to comment Share on other sites More sharing options...
cruiser54 Posted December 1, 2012 Share Posted December 1, 2012 If it turns out to not be the CPS, then the next in line would be the reluctor inside the distributor. They are pretty rliable, but do cause troubleshooting nitemares. Thankfully they are really inexpensive, so may want to just go ahead and swap it out for a new one. You really do need to verify you have voltage to the ignition components first. It could just be a simple break in a 12v wire. The sync generator in the distributor is there ONLY so the ECU can figure out which cylinder is due to fire and then fire the injectors sequentially. You can unplug the distributor and the Jeep will still run. As for HOs, that's a whole different story. Unplug your Renix dizzy harness and start it.......... Link to comment Share on other sites More sharing options...
CallmeMaybe Posted December 1, 2012 Author Share Posted December 1, 2012 Update: New Distrib New Plugs New Wires New Coil Got the Module check at the parts store and it passed, but is it possible that it is actually bad? They only hook up to the connecters and not the contacts......I havent checked my connecters going into my module, but know the "no spark" is around my module and new coil. Replaced the CPS....what a pain the a$$. Engine turns over and I'm getting fuel, checked all my grounds don't know where to go next. Is there any relays or fuses that could cause this. Link to comment Share on other sites More sharing options...
MJCARENA Posted December 1, 2012 Share Posted December 1, 2012 Take apart the C101 connector and clean it out. It is the big connector above the brake booster. Link to comment Share on other sites More sharing options...
CallmeMaybe Posted December 1, 2012 Author Share Posted December 1, 2012 Thanks everyone for the help, I got the O'l girl to start. So this is a kick in the balls but it turns out there were 2 grounds unplugged. Previous owner did a head gasket and didnt hook them up. They were small ones behind all that junk on the passanger side rear of engine block. I was so lost and just chasing wires and bam stumbled on them. Not done yet new post on Overheating! (prob why it blew a head in the first place!) PS. Darn grounds strike again! Link to comment Share on other sites More sharing options...
cruiser54 Posted December 1, 2012 Share Posted December 1, 2012 Thanks everyone for the help, I got the O'l girl to start. So this is a kick in the balls but it turns out there were 2 grounds unplugged. Previous owner did a head gasket and didnt hook them up. They were small ones behind all that junk on the passanger side rear of engine block. I was so lost and just chasing wires and bam stumbled on them. Not done yet new post on Overheating! (prob why it blew a head in the first place!) PS. Darn grounds strike again! Yep. Either they're dirty or disconnected. Link to comment Share on other sites More sharing options...
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