Won't restart at operating temperature

[dino2000]

1976 CJ5 , AMC 258 i6 / 4.2l , single barrel carb. all smog equipment in tact and passed test with flying colors. Jeep has 101,000 miles on it and I have a fairly complete service history.

I can get in this thing in the morning and it fires right up. The choke functions perfectly. I have replaced ALL of the ignition components. The fuel pump is new. I have flushed the rad, new hoses and new thermostat. It runs down the highway and around town without issue. The problem starts when you shut it off at operating temp. It will not start back up until it has sat or "cooled off" for at least 20 minutes.

I have noticed two things that are odd when this happens. The coil and resistor are so hot that you cant even touch them and the motor won't fire on starting fluid. The coil and resistor are mounted to the side of the motor in the stock location.

I have checked the carb and it DOES flow fuel when this happens. So that leaves me to believe that this must be an ignition problem. Again, all of the ignition components are new.

Magically, after about 20-25 minutes, she starts right up and runs flawlessly. My son and I took the Jeep for it's first real trail ride / overnite camping trip a couple weeks ago and it was a serious PITA to have to wait 20 mins. every time I killed it on the trail. We live so close to so many great trails and I'm less inclined to go because I just can't nail this down.

Any help would be GREATLY appreciated. Thanks in advance, Dino

 

[elwood blues]

From your symptoms it sounds like your ICM (ignition control Module) has went bad. Did you recently change that? I've gotten them from the parts store that have only worked a few months before crapping out.

 

[dino2000]

Funny thing about that Elwood. My ICM (little silver box mounted on the fender well on the passenger side) wasn't even plugged in when I bought the Jeep, had it smogged or discovered this problem..............mysterious, NO?

 

[elwood blues]

Funny thing about that Elwood. My ICM (little silver box mounted on the fender well on the passenger side) wasn't even plugged in when I bought the Jeep, had it smogged or discovered this problem..............mysterious, NO?

Little silver box, looks like this:

the thing I don't understand is that without some sort of ignition control your engine won't run . Is it hooked up now?

 

[dino2000]

i can plug it in and unplug it while the thing is running!

 

[mylittlecj5]

We need pics of your ignition system and a few of under the hood now...

It almost sounds like your carb is flooding from heat when you shut down. The fuel in the bowl expands from the heat and leaks past the seals into the engine, flooding it. when it finally evaporates/leaks past the rings, the engine will start back up again. Chevy engines were real bad for this when I was a kid. But I haven't really heard of this on a inline engine, so :dunno:
One way to check this is to smell the oil. If it smells like fuel, you have a heat soak problem.