my truck had a hard time starting after it got warm for a while. i knew it needed a ground wire and finally replaced it last weekend. starts great now except when i shut it off i can watch the voltage drop with my volt meter. after about 4 hrs its dead as a door nail. the alt is charging the batt at 14.53 volts at idle. i pulled the alt wire off and it stopped pulling power. does this sound like the reg. is bad? dont want to spend the 60 bucks if not. its a 91 with the 94 style harness and alt. just started doing this after i replaced my bad ground too. thanks guys for the help.

 

Pulling the battery from the alternator will fry the regulator. The battery is a balancing load for the charging circuit.

Pull the alt and get it tested.

Sounds like you have a current draw from something. Get your amp meter out and check the draw with the truck off. Start pulling fuses till you find whats doing it.

 

i pulled the alt wire off with the truck not running and the batt quit dropping. sorry,guess i should have said that. it sits at 12.86 and dropped to 12.58 in just a few seconds. i pulled the alt wire off and the voltage popped back up to 12.8.