The best way is through a process of elimination. I would start by checking whether there is a drain in the system when the car isn't running and the key / all accessories are off. Pull the positive lead off the battery and connect a test light or an ammeter between the battery and the lead. If you have current, there is a short in the system.
This is about the worst kind of problem to find, since all the wires are wrapped in the harness. If you do have a short, the next step is to determine what circuit the short is in.
Go to the fuse block and disconnect one fuse. Then go back to the battery and check whether there is still a drain. Re-install the fuse.
Then repeat this with each fuse until the drain disappears. That fuse controls the circuit that has a short.
Yeah! You've found the circuit. Now you have to find where in the circuit there is a short. If it were me, I would start with any switches or electrical connections in the circuit.
If it isn't a short, the problem is with your charging system. Check the voltage over the battery terminals without the car running. Then start the car and check the voltage again. If the voltage doesn't go up, take the alternator to the auto parts store and have them test it. They will do this for free.
Okay I've typed a bunch of trouble shooting info, but let me go back to the beginning. Did you have your original alternator tested? How old are the battery cables and the ground strap in the car? The first thing to check on an old car is always the ground connections. Your battery and alternator can be perfect and a $5 ground cable will strand you. If they're old and ugly, I'd say replace them just to prevent being stranded somewhere at the worst possible time.
Good luck with the problem! Please post what happens.
I have already replaced the alternator and the battery. I will have to go through each individual circuit. Thanks for the help. Ill get back to you to see if this works.
Does anyone know how to properly wire an alternator. It is a 4-wire harness, one red - positive, one black - negative, and 2 other wires. I have 5 slots total. Positive connect, Negative connection, 2 metal to metal connections, and a connection witha plastic back. Much help is appreciated!
Have you considered installing a battery disconnect switch? I have a similar problem on my 65 coupe and have not had any luck locating the current drawing source. At summit racing's online store, there are bunch of switches for sale.
I'm not sure which one to try out. If anyone can give me any feedback I would appreciate it!
I'm no expert on the '73, but does it have a separate alternator regulator (on the '66 it's on the driver's side front panel in the engine bay). These are really crummy electromechanical devices and go wrong all the time.
You could have bought a defective alternator - get it checked.
Yeah, it was a defective alternator and regulator and it fried my battery with it.
Everything went wrong, I've replaced it all and its okay, but still has draw upon the battery somewhere. When i turn on my headlights, the engine dies also. Any more suggestions?