Engine shutting off at random

The 258ci in my '75 CJ5 will shut off at random. But not like it's a fuel problem, more like electrical but I can't find it. Almost like you're driving down the road and just turn the key off. Then there is a swooshing sound as it dies. Anyone experienced this or know what's wrong?

 

could it be a short in the ignition switch/system that acts like you are shuting it off?

why do you think it is not a fuel problem? b/c it doesn't die slowly?

 

Yeah, I would think if it was a fuel problem, it would cough and sputter out. It may not NOT be fuel related.

 

Like Kercher said, it could be the ignition switch, had something similar happen to me. When it does it next, wiggle the key and see if it starts running again.
What kind of ignition system do you have? I would think you have points, could be a wire in the distributor that is broken or shorting, or a feed wire, etc. causing this. If electronic, what type do you have? Some fender mount modules are notorious for this, especially the Ford-based units. A simple module replacement usually fixes the problem. Also check all engine to chassis grounds and ignition to chassis grounds closely and make sure they are clean with good connections as they can cause intermittent issues like this.

 

A '75 will have the Prestolite electronic ignition. The Prestolite system is well known for driving along and just quits. Pull over, put the hood up for a while, and it starts again.

The Prestolite system uses a distributor with a plastic vacuum advance can.

The trouble comes from the module, or from the sense coil in the distributor, or from bad contact in the connections between them. Most likely you need a new module. You can replace the module, but if it were mine, I would not bother. Instead, I would replace the whole ignition system with a GM HEI distributor, or with the '78-on Jeep Duraspark system.

 

I had a similar problem with a '74 CJ5 with 258 that I had about 23-24 years ago. Mine was caused by a bundle of wires that were wrapped together and as I recall they were in the grill and crossed from one side of the Jeep to the other. When I unwrapped the factory wrap around the bundle of wires I found that the insulation on two of the wires was worn through and they occasionally met, killing the ignition.
It took months to find, and the problem was very intermittent. The symptom was just like yours, I would be driving along and it was like somebody turned off the key. Happened to me once in the middle of nowhere near Contact, NV and I got serious about finding it.

 

I also had a similar problem with my '75. It wasn't untill months later when I rebuilt the Jeep that I found the culprit! It was a black wire inside the distributor, that was connected to the movable advance plate. Over the many years and miles of use, the wire moved back and forth with the plate,,, untill it fatigued and broke the wire strands inside the covering at the connection to the plate, ,,, It finally broke all of the wire strands, and as long as the wires were touching inside the plastic covering the engine would run just fine, but at times, it would just disconnect and make the engine suddenly stop. The plastic covering on the wires stayed intact, so I couldn't see that the wires were broken.

Hope this helps
SPW