[DeTomaso] Weird Charging System Problem

[J. Sean Keane]

I have a charging system problem that I should be able to figure out, 
but can't seem to. Any advice is appreciated.

Several months ago, I swapped out my stock Motorcraft alternator for a 
high-amp model (80 A) because the battery never seemed to get fully 
charged, and would slowly lose power and require periodic charging. This 
was after I bought a new battery, which was my first suspect. Recently, 
the ammeter began showing a large discharge no matter what the engine 
RPM was, so I swapped the old alternator back in. This cured the large 
discharge, but the voltage across the batter is only 11.58 volts. I had 
also changed the voltage regulator when I changed the alternator, but I 
replaced the voltage regulator again, with no improvement.

When I rev the engine, the ammeter goes slightly positive, but just 
barely. The generator light on the dash is constantly lit. Any ideas 
about what else to check? Whenever I've had charging system problems on 
other cars in the past, it's always been the battery, alternator, or 
voltage regulator. This one doesn't seem to be any of those things, 
unless I've got the wrong voltage regulator or something (the wiring 
harness fits it, though.) Any suggestions are appreciated.

Best Regards,

J. Sean Keane