Force voltage regulator(s)

I have a 1987 125 hp Force outboard motor, model #31251x7a. According to our electronic instrument the alternator is bad. I am guessing that the alt. is a switch box or voltage regulator. I am showing in iboats.com a switch box part #116-3301 for replacement. I find two switch boxes on right side of motor w/ the colors of black and one blue. Which one should I replace?

Re: Force voltage regulator(s)

I assume you mean the starboard side of the motor. Those boxes are the CDI ignition modules. They have nothing to do with the charging system.

That engine does not have an alternator, it is a stator based charging system. What problem are you trying to fix?

Re: Force voltage regulator(s)

Most older OB have alternator (the stator) that makes AC and the rectifier changes it to DC. You can check them with a cheap meter, the non-ignition wires from the stator/flywheel go to rectifier and have AC voltage when running. If you don't get an increase in your 12v DC at battery when you fast idle the motor, or have lots of AC voltage in the 12v DC at battery then the rectifier is bad. If it has a voltage regulator it will be different. The stator wires that go to the ignition box(es) are for ignition. Usually the tach wire will go to the alternator wires, actually one of them. Most are easy to follow the wires but some run the tach wire into an ignition box so you can't see what it goes to.

Re: Force voltage regulator(s)

Thanks for the replies. This is impressive to get so much help and information. The motor does not seem to recharge or maintain battery power upon use. When I get the chance I will check the battery lead wires to see if the stator is responding upon fast idle. Thanks for the information.