Alternator 350 MAG MPI

[srvwhoscw]

Hey guys,
I cannot seem to repair what I thought would have been an easy fix.. I put in a new alternator for a 2007 SR 240- 350 MAG MPI. Old alternator was reading 25 volts, not charging batteries. We figured must need new one. We replaced alternator, dash gauge read 14.2 volts. 10 minutes later it went down to mid 11's. When tested the same reading at alternator. 25 volts... We must have blew the diode or regulator but do not see any visible short. Would the 90 amp fusible link cause the alternator to go bad? If the orange wire from the alternator was too close to a sark plug wire (it was touching) cause the alternator to blow again.

Any help would be much appreciated.

 

[JimG]

Not sure where you are measuring 25 volts on the alternator. With problems like this, I won't trust the dash volt meter. Using a quality volt/ohm meter, measure directly on the battery with the engine off and then with the engine on. Under normal conditions, you should see ~12 volts DC off and ~13.8 volts DC on.

It's not clear where your 90A fuse is, but a blown fuse directly on the output of the alternator could make it read high... a no load condition is not recommended for alternators.

A spark plug wire near alternator wiring will not cause a failure.

Maybe this 90A fuse is your problem... :huh: