Posted by Joe Divito (IP: 207.239.0.99) on February 01, 2000 at 21:38:45:
In Reply to: 76 ford Mavric posted by Brian Lee Hunt on January 31, 2000 at 19:46:30:
I'll take a stab at it. Have you checked the voltage regulator? There was a guy on one of the Mutang web pages who had a similar problem, and when his alternator went, it took the voltage regulator with it. Also, are you sure that the alternator's belt is at the proper tension? If there's any slippage, you're not going to generate enough power, even with a new alternator and belt.
To see if the voltage regulator is getting enough juice to the battery, get a volt meter (or multi-meter set to measure voltage). With the engine running at idle, you should see at least 13-14 volts at the battery's positivle terminal. Adding an electrical load (such as turning on the headlights) shouldn't reduce the voltage significantly. You shouldn't see a huge increase in voltage if you rev the engine either.
Any major deviation would indicate that the voltage regulator is shot. They're pretty cheap, so if your's is old, you probably would want to replace it anyway.
Good luck!