Voltage Regulator or alternator

[Jsiples]

140 h.p. Mercruiser I4....was out running the boat yesterday and voltage at dash was spiking and dropping erratically. Lights were surging also so I know it is not the guage. Then it just stopped and battery guage will not move even at high speeds telling me I have lost charging system. Checked belt seems taught. Would this most likely be the alternator or could it be the regulator, the only reason I ask was because of all the surging that went on prior to no charging at all.

 

[Haut Medoc]

Re: Voltage Regulator or alternator

I would check all of the electrical connections....
While I was doing that, I would take the alternater to a Schucks or whatever auto store is nearby & have them test it.....
That would be the easy way to see if it is the alternator or an electrical connection, IMHO......​

 

[WillyBWright]

Re: Voltage Regulator or alternator

Make sure your battery connections are clean and tight. Most sterndrive regulators are internal to the alternator and not separate parts.