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1983 Jeep CJ7

I have a 1983 CJ7 258 inline 6
Mechanic says coil is only discharging 12 volts on release of the key. It takes so long to crank that the battery ends up dying. Carburetor has been overhauled, gas tank and fuel lines have been cleaned and flushed. Mechanic said there was a leak in the intake but think it is remedied. Will start but can’t keep it running unless gas pedal pressed. If you stop to shift gears, turn, etc, it dies.

Check to make sure the intake leak is fixed. If not, the leak causes the carb to run very lean, causing you symptoms. If it runs at all, the coil is a red herring.

Is this old enough to have a ballast resistor? That is just what a failed ballast resistor did.

Is the electronic Carter carburetor still on the engine? The carburetor and the electronics that controlled it were obsoleted by Jeep long ago. If the carburetor is not functioning properly replace it with a carburetor for 1979 and earler models.

It sounds like there may be more than one issue here, but I concur with oldtimer11 above that the ballast resister and its bypass (during cranking) circuit should be checked.

For the poor running performance, well, auto engine technology is pretty much the same now as it was 100 years ago. Any gasoline engine will run well with a good spark, correct ignition timing, correct fuel/air mixture, correct valve timing, and compression. You just have to go through those one by one. The question is where to start? In the absence of anything visually out of order, like broken or missing vacuum lines, I think I might put a vacuum gauge on the intake manifold as the first test.

Edit: One obvious thing to do I didn’t mention is to check for any diagnostic codes from the engine computer, if this vehicle has such a thing.

@BudJ‌

Before doing anything else, I would check compression

If your compression is low, you’ll have a heck of a hard time starting the engine. It’ll take so long, by the time it stays running, you’ll have almost killed the battery

My brother’s car . . . not a Jeep . . . had the exact same long cranking times, which really messed up the battery. It had low compression. After adjusting the valves, the compression was up, and it started instantly, every time

Maybe your compression is fine. I’d just rule it out as a possible contributing factor, before testing all the other stuff

If the compression is good and if the main issue is dying with the foot off the pedal then the possibility of a vacuum leak or a carburetor problem involving an idle circuit could be the cause.
Not being terribly familiar with this setup, I might add that if the carburetor uses an anti-diesel solenoid, which is common in this era, a problem like this can occur if the solenoid is faulty or electrical power is missing for whatever reason.

Knowing how the carburetor was overhauled may provide a clue. There’s more to it than hosing it down with carb cleaner and installing a new kit. Not saying this is the case here but this method is not that rare; and wrong.