p25486

Hi, I have a 73 mustang, 351C.

I've been having some issues getting it started lately. It sits for long periods of time and the gas evaporates from the carb. It take quite a while for the gas to get back to the carburetor when cranking for the first time in a few weeks.

It takes so long, that I had issues with the starter relay getting too hot and corroding the contact to the starter motor. I have in the past been able to get things going again by taking the starter cable off, brushing it with a steel brush and then returning it to the starter relay.

But not this weekend. I cranked it for quite a while, till the battery started to run down. I stopped and recharged the battery. I noticed that the starter cable was more toasted than normal. So, I decided to replace it. Since it had got so hot, I decided to pop for a new starter relay too. Then I got crazy, and replaced the regulator and the coil too.

Everything replaced and installed, I was ready to try and crank it back up, but when I went to reattach the battery ground, there was a large spark!

Got out my ohm meter. Sure enough, dead short from 12V input to the starter relay to ground.

I started pulling things off the starter relay to see if I could narrow it down. When I took everything off the input side of the starter relay, the short went away. So, the new starter cable to the starter is ok.

Next I started hooking up things on the input side. First the battery cable from 12V. No problem. But, there are three others things that are connected to the input side. Any one of the three appears to cause the short.

What are the three things? What do they go to? What is broken?

Thanks to all,

John

p25486

More notes.

When I had this car restored a few years ago, it came back to me with a slight mis-wire on the starter relay. There's a relay for powering a heater for the choke, and they put it on the battery side of the switch so that my battery would drain in one day. I fixed that.

With this new problem, I'm wondering about the other wires on the battery side.

There are two with fusable links, so obbviously for the battery side (one has a black wire the other yellow, both go to the harness).

Another has a large device in line, maybe a resistor. I remember this always being on the battery side.

The fourth is an aftermarket wire that attaches to the case of the alternator. Noting that the engine isn't grounded, and that the lug on the alternator is a short to the engine, I summarized that this was supposed to be a supplemental ground. It is likely that the end was broken, and I fixed it. Yay me.

So, did I blow up the alternator?

I can connect the wire with the resistor without a shorted situation.

If I disconnect the voltage regulator, one of the fusable link wires no longer causes a short. I don't recall which color fusable link wire was ok.

But the other fusable link, and the wierd alternator cable cause a short whenever they are connected.

Can I test the alternator?

Thanks,

John

p25486

Ok, I think that I've figured it out. But, I'd like to have someone tell me where the yellow and black wires with the fusable links are. The ones that attach to the battery side of the starter relay.

After thinking about it, I realized that the car restorer made a mistake in connecting the extra alternator ground wire to the battery. The reason why the connection looked broken to me, was because it was broken. Burned through even before I picked the car up from the restorer.

In my ignorance, I fixed that wire. Thus the spark.

The other wires float cause the ground to float up to 12V because there is no current flowing and no real ground. I suspect that if I reconnect everything, but leave out the alternator's alternative ground, then all will be fine. Sounds like a tomorrow project for me.