starter problems
 

I have a couple of questions about the starter in my 79 911
1. should there be juice going to it through the heavy wires even when the key is off ?
2. I tested the spade connections and they are only hot when the key is turned.
3. The starter worked fine before it was taken out to rebuild the engine.
4. Are there any test I can do to make sure its the started?
my thank in advance.

I'm no expert when it comes to electrical. However, you may want to give a few auto parts shops a call. Some shops have equipment to test starters, alternators and the like. Take your starter down and have it tested. At least then you'll know if the starter is good.

Yes it should always have power to it

You may want to reverse the 2 small wires on the solenoid , I had the same prob after reinstalling my motor and switched the wires on the solenoid it started right up

The big wire to the starter goes directly to the battery positive terminal so it always has power. The yellow wire is the trigger from the ignition switch and should only have power with the key in the start position. The above mentioned (switching terminals) is a possibility. The other is the transmission ground strap. This is the main ground path back to the battery for the starter and is very crucial. It attaches to the nose of the trans. and to the rear of the center tunnel. If it's either not there or poorly connected (or corroded) replace it or tighten it. If none of this helps I'd suspect the starter.

I agree that you should check the transmission grounding strap if you are having problems with your starter. An old or corroded one will cause intermittent problems to an otherwise perfect starter... it also affects many other things. I added a second one to mine and all my engine electrical problems disappeared.