My 460 is in a 1995 jet boat. I've been struggling to get the batteries charging. I initially replaced the alternator but no change. When not running, the meter shows battery voltage at the back of alternator indicating a good connection. When running, the meter shows .4 -.6 volts at the back of the alternator. When I bypass the connections and run the negative post on alternator to ground, it shuts down the engine. I took the alternator back and it tested good. Any help would be greatly appreciated.