The thing stoped running for no reason, please help !!!

Hi all


I went to put gas in the CJ after my gas tank skid plate swap this afternoon. The engine was running great, no apparent problem. In my way back, it kinda lost power very fast, (just like when you press on the clutch and release fast). 2 second later, a small ``bang`` (like a backfire, but less noisy), and it just died. No way I could start it over, I had to call a towing to bring it home.

I did an engine swap this winter, and I tought I was over with troubles. It is not the first time I take it out after the swap, I even got to a trail day and it was great.

Fuel is coming to the filter, and also pass it. I will check tomorrow the rest of it, I was so frustated I decided to do something else tonight.

Here are the things I did not swap yet, if you have an idea, please let me know.

1. Can it be a symptom of ignition box (the one in the fender) failure ?
2. Can it be the timing (we did not check this after the swap, but it ran great)
3. What else can go wrong ??? What is vaporlock ? can it be it ?


I'm kinda lost here, I'm very disapointed at this, again in trouble, please help !!!


Thanks a lot, I do appreciate


Bob in Sherbrooke, Province of Québec, with a problematic CJ-5


p.s. I have an 83 I6, but with the 1bbl carter carb from my original engine. The carb is new from last year

 

First place I'd check is coil, followed by ignition module.

 

Hi

Someone suggested that the timing chain may have skip a teeth, which would explain the first behavior, followed by the stop.

What do you think ? Is there chances that internal parts of the engine where broken in the process, if this is it ? Let's hope it is not that bad, otherwise a lot of CJ parts will be for sale soon.....


Thanks to all

Bob in Sherbrooke, Province of Québec

 

Just a thought...Do you think you could have put in some bad gas? You stated that you were retuning from getting gas when the problem started. I had that happen a few years ago and I had backfiring and power problems. I think it was water in the gas in my case. Actually it happened on two different occasions from the same station. Rick

 

I don't think it's the timing chain, unless it broke completely. Usually you'll jump a tooth or two and then it'll barely run or almost start, backfiring and popping.

I think the module is the most likely candidate. If you look down the carb throat and see fuel, then you need to think about spark. A bad coil is possible, but I think the module is more likely. Some parts stores have a tester for these, or there may be a test procedure in the FSM. You can test the coil with a multimeter.

<edit> OOOOhhh, this is a '77. You have Prestolite ignition. The Prestolite module is notorious for just quitting. Also check the module ground, and make sure the connector to the distributor is scrupulously clean. The reluctor (coil thingie in the distributor) also sometimes fails. If it were mine, I'd upgrade to a GM HEI distributor, or the Duraspark with TFI parts from a '78-on Jeep. '77 was the last year for Prestolite...

 

First, I'd check is the ignition. See if your getting spark. IF you just getting 1 spark then it's probably your ignition module. very common.

Vapor lock will go away when the engine cools. THere is a special 3 port fuel filter that helps prevent vapor lock if you are having that problem.

If it's your timing chain it will still be lose after jumping so you can check if it's still sloppy. I think Lynn has a good post on that someplace.


<Edit> I started typing a response at 6:00 AM this morning, by the time I finished after being interupted with work everyone already answered your questions. I'd second the GM HEI suggestion. </edit>

 

i had a 76 that would do the same thing. turned out to be the large wiring connection at the firewall. i "straight-wired" it (jumped around the connections, and never had the problem again. good luck

 

Hi all

Finally, after checking the relationship between the distributor, the #1 wire and the #1 cylinder, we found out that indeed, the timing chain ``jumped`` a teeth on the gear.

So now the jeep is radiator-less, and we are stopped because we will need a puller to remove the pulley. All of this done under a less-than-perfect tarp, and rain.

So tomorrow I'll order new gear and chain, and hope to get this soon enough to try to finish the job tomorrow night.

Thanks to all for the advise


Bob

 

Look on the bright side, this could have happened 4 months ago... brr!

 

Yes, or in the middle of the wood on a trail ride. This with a direction problem I think is the worse that can happen in the woods, this is not something easily fixable in the middle of nowhere...


Bob in Sherbrooke, Province of Québec

 

Well, the mystery keep going

Ok, ok, ok, it is not the timing chain. We opened it, and it did not jump a teeth. At least not according to the Haynes manual....

BUT, it is sloppy by a little bit more than 1/2 inch, so I,ll change it anyway. I'll see tomorrow if I can borrow a ignition box, the damn thing cost 100$ and cannot be refunded.


Ah well, this is how we learn I guess.....


Bob in Sherbrooke, Province of Québec

 

I dont know if you have points or not, but on my 74 i had a control box with a points and condenser style distributor. I pulled out the control box and replaced the points and condenser and she runs great.

crank the engine over with this distributor cap off, and make sure that 1) the button is turning, and 2) that the points open and close.