I bought an 80 amp alt from a 95 240sx-se and had a pulley machined to adapt to my car. my current stock alternator is ok, i.e. it charges back to the battery, but only after it runs a while and i rev the motor to around 3K. so i installed this new one and it won't charge back to the battery at all...my volt guage (in the car) needle locks at about 13.5 and stays there. normally i would see it swing up to just behind the 16 mark, but this thing does not move. what could be wrong?