voltage problem 74 duster

[aa-1159]

bought a tricked out duster with a mitsubishi alternator puts out 12.5 volts
car has elec. fuel pump, msd, 2 elect. fans, as car runs voltage seems to drop off, if you turn on a fan without revving up motor car cuts off
put alt. from my 73 on 74 and is only putting out 10 volts
single wire alt. with one field wire, need help real bad
[email protected]:wack::wack:](*,)

 

[340mopar]

12.5 volts is not enough, it should be in the 13.5 - 14.1ish range when running. Might be a dead diode, regulator, ? Take it somewere to have it checked.


Chuck

 

[player1up]

That is whack..

any more history on the car.
like why did it have a new alt put in?
or Did the guy wire all of the new electrics correctly?
Some of the most hellish electrical problems come from one little thing that takes out the whole system. One little thing wired wrong, or too much load for the system or wires. (don't forget that the wiring in the system is just as important as the other components.)
I could go on and on..sorry

 

[Dusterb318]

Are there relays on the pump and fans? If not there is a big problem. Is the factory wiring harness still being used or is it an aftermarket style? Stock voltage regulator?

 

[dgc333]

12.5 volts means the system is not charging at all. The nominal voltage on a fully charged 12 volt battery is 12.8 volts.

If it is a single field wire alternator and it's a 74 car you will likely need to switch back to the old style voltage regulator. The wire from the regulator to the alternator in the 74 style system switchs the field winding to ground. Sounds like the Mitsu alternator needs needs the regulator to apply voltage.