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I have a 68 Fastback with a 428 CJ that sat for 33 years, and have been working on starting it. Drained and flushed gas tank, rebuilt carb, new battery and starter solenoid, plugs, changed oil, hand-cranked engine, etc. It cranks fine and starts to run while cranking but when I release the key to the run position, it dies. I had lost the ignition key and replaced it with a lock I had a key for. I'm thinking it may be a faulty ignition switch, but after sitting that long, it could be anything. Any suggestions as to why it would light up during the cranking but die immediately after?
 

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Iowan gave you the right answer, but the "why" is the solenoid feeds the ignition while cranking, then when you release the key, the resisted run circuit takes over.

For whatever reason, when you release the key, the run circuit seems to be dead. Check for power on the pos side of the coil sitting there key on, engine off. If none, need to find out why. Could be ignition switch, could be wiring, also make sure the small wires are connected to the battery side large post of the solenoid, that feeds the inside of the car with power
 

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Sorry for the slow reply - I had trouble signing in.

Thanks for the suggestion. I followed it that night, and no- I did not have 12V at the coil. I checked the resistances across the coil and they seemed right, and I replaced my ballast resistor (since it was cheap) but it too gave the same resistances as the old one. I have an ignition switch to install, and will see if this solves it. Else, I'll need to find out where, between the switch and the coil I am shorted ?
 

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Discussion Starter #5
Thanks 427stang - I really appreciate the explanation. I seemed to recall that there was a switch in power flow when releasing the key. I expect it changes which of the large posts in the ignition switch connect to the third large post. Anyway, I will read up on the resisted run circuit to understand it better. I plan to replace the switch soon (have a new one ready) to see if that is it, as suspected. If not, I'll need to start tracing. And yes, the solenoid is hooked up and I have power inside the car.

Thanks again!
 
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