72 Mach1 intermittent starting

There are two things that kill a battery the starter and the horn. I assume you did a current draw on both? If not take the starter down to an auto parts store and have a current draw test done on it. for the horn a simple thing to do is disconnect it and see if the battery is still discharging.

I had similar problem,

could be the starter solenoid, itself, I found one (a brand new one) the internal ground wire was not even connected, just lying on the chassis ground, piece of shit china junk. Replaced it, now OK, but could be same china pos.

try testing the solenoid by itself, disconnect heavy battery lead, by applying 12 to the terminal, should be loud click, mine was intermittent, replaced it again now ok.

You list the car as a mach 1.Starter not even working no click nothing? Some mach's mostly big blocks though had a starter overheat module just below the solenoid. this was to stop from melting the battery cables under the high load of the big block starter.

Other than that like everyone else I'd say starter solenoid has a heat problem and needs to be replaced.

10-1 > minutes, then come back home and shut it off. I try to turn the ke > again and nothing. No starter motor, not even a 'click' sound fro th > starter solenoid on the wheel well. Open the door and the dom ligh > comes on as it should. Turn on the headlights and they light an don' > visibly dim after 30 seconds. Last weekend I tried checking all th > connections between the starter, starter solenoid, alternator, an > ignition on the column. Thought I had it licked when it started bu > same thing happened again. I've already replaced the alternator an > starter solenoid. What to do now? I'm hoping I can put off rewirin > the whole car until I decide what I'm going to do about the engine > but I'd like to at least have it running reliably until then. An > ideas >

I've had Ford small blocks in classic Mustangs fo

30 years. They are pretty simple configurations compared to the newe motors

From what you have described, the problem obviously is in the wirin

or an item in the wiring. The fact that the wiring has been patche is a sure red flag and likely where the problem is. The batter running down if you leave the battery attached is pretty unusual Short of leaving lights (or a horn button short) on I can't think o what would cause that other than a short in that wiring. I woul replace the harness to eliminate that as a potential cause

Another thing you should check just to eliminate this is the ground o

the block. Take it off and sand the rust off the end and the block. I there is not a good ground, it won't turn over. And if you haven' cleaned this if could be giving you some intermittant problems. Thi is a pretty easy thing to "fix". It might be rusty enoug and/or loose to be causing issues. This would not run your batter down though