Alternator / Charging issues
 

I have a 1981 911 SC Targa (i think my screen name may have given that away) that I finally brought home after over a year of body / paint work. I have put the car back together mostly, but now I have to deal with an issue that I have been putting off for a while.

When I turn the key, the Battery light comes on as it should. When the car is started, the light turns off. When I first start up the car, I get about 13.8 V at the cigarette lighter, showing me (as far as I know) that the alternator is doing its job charging. This will teeter between 13.5-13.8 as long as the car is NOT at normal operating temperature. Once the car has warmed to normal temperature the voltage drops to 12.0 V or less and continues to drop and the Alternator appears to not charge any longer.

I am wondering if it may have a short or something in the O2 sensor circuit (i may be way off). If I remember correctly, until the car warms up the Warm Up Regulator takes care of the Air / Fuel mixture, but after that the O2 takes over.

Other than that I don't know enough to really have any educated guess as to why this may be happening, but hopefully that's where all of you come in.

Any ideas?

Thanks in advance

http://forums.pelicanparts.com/uploa...1214852932.jpg
Pic of the car right after paint (taken with my cell phone - in the paint booth in my dad's barn)