75 CJ-5 Prestolite Ignition System Woes

[Koko4]

I have been battling my CJ5 for months and months now. It started with an EXTREME hesitation while accelerating. I would also have to fight it to even get it to start. The other day, it stopped wanting to even TRY to turn on at all. It will turn over and turn over, but never even try to choke to life. I can see the gas spraying into the carb, and do not suspect the carb as the problem.

I towed it to a friend’s house the other day and we were able to get it to crank. We were not able to drive it, because as soon as you try and give it gas, it wants to die unless you REALLY feather the accelerator. At idle, it sounded strong and I couldn’t really hear anything wrong. While listening to it idling, he said it sounds like it has a miss at idle, though. Not really knowing what the problem was, he said to try replacing my spark plug wires and if that didn’t work, to throw another distributor on there. He said he was fairly certain it was ignition-related, and not fuel-related.

I hate throwing parts at it, but today that is exactly what I did. I had Limited Lifetime warranties on these parts, ALL of which were replaced today with new ones from the store: Ignition Control Module (gold Prestolite box), Distributor, Rotor button, Ignition Coil, and wires are only a few weeks old. Spark plugs were also replaced a few weeks ago with ACDelco’s I believe, and I checked the gaps as they went in.

So with that being the case, the Jeep STILL wouldn’t start today. No spark either. A little bit of history on the Prestolite Ignition System – the wiring is “custom”, so-to-speak. The wires had to be connected individually. We did this a few summers ago – a buddy and I went to a lawnmower shop and managed to track down some of the same connectors that the Ignition Control Module uses (the male / female square ones), and we wired everything – one wire to the negative coil terminal, one to the positive, and two to the distributor. The Jeep HAD run and driven in the past with these wires like this, so I had always assumed them to be correct.

Well, today I decided to double-check the wires. I checked them all for continuity, and then labeled them 1,2,3, and 4, and started making sure they were following the routes according to this diagram:
No spark with new coil on V8 304 - JeepForum.com

They weren’t in the right spots. I actually had to cut and re-splice two of the wires with butt-connectors, and I just finished wiring it up according to the link above. I won’t have a chance to test it until tomorrow.

My question is would the Jeep have run with the wires being incorrect?! I’d assume not, but I mean..I guess it could be the reason for the super-crappy acceleration / hesitation under load, as well as how reluctant it has been to start, literally almost EVERY time I have tried starting it?

Also, there is no way for me to determine how the two wires coming out of the distributor need to be connected to the ICM. I mean, I could have them flipped and wouldn’t know (no positive / negative that I can tell of, or no color coordination either?) Can anyone help with that?

If this doesn’t work, I am seriously considering just upgrading the ignition system. I wouldn’t know what to go with, however. I have a friend that was saying to go to a points distributor, that way I could eliminate the stupid Ignition Control Module, as well as a bunch of wires, from the equation. I have read a bit about the DUI, HEI, and Team Rush upgrades, but don’t really know which would be best for simplicity… This Jeep has a rebuilt AMC 304 , but it’s all stock specs, and I don’t plan on doing anything too crazy with it (oversized tires, changing gear ratios, etc). I just want it to run well, and run strong. I don’t want it to be overly expensive, but at the same time, I don’t want to cheap out and get something unreliable. I just want the system that is the simplest and will get the job done. This is all IF I decide to upgrade..which, honestly, if the Jeep doesn’t want to crank tomorrow, I will probably end up doing.

Well thanks for making it this far through my post. I am at wit’s end with these issues!!

 

[Torxhead]

It sounds like you might have some carb issues also. The coil could be a factor also, so check that. The ignition does need to be changed though, most guys with the prestolites usually go with the D.U.I. for simplicity, but a swap over to the Motorcraft and the newer type icm is less expensive.

 

[Hedgehog]

While the Prestolite ignition isn't the best and I'd change it to some sort of one wire HEI dist. (and I did just that) I doubt a couple week old properly wired Prestolite dirtributor would have gone bad. I simply can't believe it.

It's probably writen in onee of your posts, but I haven't seen it, haven't looked either, did the jeep run BEFORE you worked on the ignition system the first time? If so look at the work you did, if not the ignition system is not your problem. Engines are generally fairly forgiving about ignition timeing issues. They will start, they will accelorate, thy might run rough until timing is brought under control, but they will run. I beliee your problem is elsewhere, primarily in the fuel pressure side of things. Which brings up the question:

Have you checked your fuel filter and fuel pump?

 

[73CJ]

Your symptoms sound like my 74 AMC 304 did when the timing chain jumped a tooth. I burned out a starter . . .it really wanted to start Ran fine when I parked it. Next time it wouldn't start.