I’ve just got my hands on a 72 Cutlass Supreme and have been through an alternator and a battery. I’ve taped up every loose wire I could find, and I still can’t start the car after it has set for more than twenty minutes. Any suggestions because my next step is to rewire the entire thing and I really don’t want that.
Have you tried tracking down the leak by checking the current through each fuse when its shut off?
Are you saying that the engine won’t turn over, or the engine turns over but won’t fire up after the car has set for 20 minutes after being run?
If the starter won’t turn the engine over, try jump starting the engine. If you get the engine started, run it for a while then shut it off and disconnect the negative cable. Let the car sit for 20 minutes, reconnect the negative cable and try to start the car. If the car starts right up, then there really is a current drain and a pretty severe one at that. However, I can’t believe that this would be the case or you would probably have burned up the wiring in the car. If the car won’t turn over, then I would suspect either the battery is defective, or it isn’t being recharged by the alternator. There is also a possibility that either the engine is binding when it is hot or the starter or solenoid is heat soaked. I remember the 1974 Chevrolet Monte Carlo we had had a heat shield around the starter solenoid. It rusted and shorted the terminals. You would know if this happened, because there would be fusible links that would burn out. Try starting the engine again when it is cold.
If the engine cranks but doesn’t fire, then you have either ignition or fuel problems.