Hello starter help!
 

Hello, I have a 1978 911SC with a starting problem, no starter activity at all. Car was starting fine, then I let it sit for a month (outside!) and now nothing. Here's what happens, with a turn of the key the ignition turns on, fuel pump runs, lights work, etc. However, when turning the key fully over, nothing happens except the speedo needle swings up to 50mph and then back to 0. I have removed the starter and tested it and it works fine. So I think I have it wired correctly, the battery is fresh, and the starter works with a direct power source. Ignition switch issue? Ground issue? (I've looked and the main ground near transmission tunnel appears ok). Thanks for any help.

One of the best starter troubleshooting articles that I have come across is in a 914 Tech Article:

Pelican Technical Article: Starter System Troubleshooting

When you say, "The battery is fresh," does that mean you've charged it since the car sat for a month? If you haven't, I'd start there. I've run my battery down to the point were my car acts like your car, with the except of the fuel pump, due to accidentally turning on the interior lights when opening the glove box. In the day, you can't tell they're on, and over time it kills the battery.

Good luck,
Mike

If your battery is low, it's not going to start. If the battery has 12.5v or more it should start. Test it with a voltage meter/gauge.

Sometimes a good whack with a mallet on the solenoid will free up a balky starter.....IF the battery is up to it.

If you haven't gotten this resolved yet, I had a similar situation. I caused it but suggestions from a competitor site suggested I remove all the +&- connections back there, including the grounding strap to the tranny, clean em & put it back together. Simple but it worked for me.
Luck>>