Help - Engine cuts out and will not fire until cools off

[bhuggins25]

I have a 1978 CJ7 with a remanned AMC 304 . My current problem is that it loves to strand me on the road. It starts fine and I normally let it warm up before driving. Once out on the road (normally 10-15 minutes out) it cuts off completely. It will not fire even if I pop the clutch. It just rolls to a stop. It appears to be a "heat" issue as after 15-20 minutes it will start up again and drive for a few more minutes. I have replaced the ignition control module, the distributor cap and rotor, and the spark plugs and have ordered new wires. Most everything on the Jeep is stock (or replaced with the closest thing to stock).

Weekend warrior these days although it used to be a daily driver.
Thanks

 

[Lumpy Grits]

Coil get'n to hot to hold?
Could also be ICM or the dizzy's pick-up coil.
LG

 

[Torxhead]

You could have bought a bad icm, put you hand on it and feel if it is hot to the touch. A bad ground can kill it also. Check that coil like Lumpy stated along with the pick up coil in the dist.

 

[hdgapeach]

Speaking from experience here so, take it for what it's worth; Get yourself two (yes, 2!) quality ICMs at the parts house of your choosing. Swap one new ICM for the one you currently have installed to see if that eliminates the issue.

The second quality ICM should go in your console, "get back box", or wherever you put spare items in your rig. That second ICM will keep you from getting stranded because of a failing ICM! Eventually, they all can go out on you. Having a spare on board does wonders for peace of the mind.

Back to the issue! If that new ICM doesn't remedy the issue, all of the previously mention electrical items in other posts are possibilities to look at. Don't just throw parts at it! Diagnose it and replace what causes the problem. Reason I stress this is because I had the exact same problem as you are experiencing now, maybe a little more sporadic. I swapped out my ICM and still had the problem. Confidence in knowing that my new ICM was good made me look to other things that would cause this problem. Extremely long story short, my mechanical fuel pump was in the process of failing on me. Would run great for a while, then the engine would die. Coasted to the side of the road, immediately change out the ICM and what do you know? NO start. But a few minutes later I got it back going again and made it home. Happened again a day later. I looked at the clear fuel filter I had installed just in case I had a clog causing the problem, and noticed it was empty. Pulled the dip stick and smelled gasoline in the oil - Fuel pump! New pump and an oil and filter change and I was good to go again (for a while).

 

[Neuner]

Ditto on the ICM. I had to go through a couple of new ones until I found one that was good. Same symptoms as you.

Not sure if it was luck or the version I got but the BWD Select from O'Reillys is the one that worked.

 

[Torxhead]

I would say that the Echlin brand from N.A.P.A. is about the best icm, and the price reflects that. Of course the MSD system would top that, if you want to spend that kind of money.

 

[Saddle Tramp]

Other than the electrically mentioned I have to agree with the fuel pump possibility. When going out a mechanical pump will leave you on the side of the road then start up and again after a little time however eventually they just die. Having said that, my father-in-law had a similar problem with his Rambler years ago. Same symptoms, start and run when cold but once hot it would die until cooled down. After stumping the pro mechanics for about 6 months the plan of attack was to change out the engine wires one at a time. Turned out the wire from the coil to the distributor was bad. It had a break in it that was fine when cold but once hot the wire would expand to the point that the break in the conductor would expand to the point that it would loose conductivity. I’d try that wire first.

 

[mriplaybass]

I agree with everything above, so I will add a bit more. When it dies, remove the air cleaner and pump the accelerator a few times. Do you see fuel squirt into the carb throat? If not, you definitely have a fuel problem. You should have a fuel filter with 2 fittings on one end and 1 fitting on the other. The 2 fittings should be parallel vertically.

 

[mriplaybass]

Oops! Forgot to mention, the smaller return line should be on top.

 

[Fastatv]

I was going to to jump in here but it looks like other members have the bases well covered for you. Should be spark of fuel, when it fails again, just test as the others have mentioned. Keep us posted.

 

[JimsCJ5]

Classic coil-going-bad symptoms. Next time that happens pull a spark plug and check for spark.