I have the same Prestolite in the upper left corner: http://www.ebasicpower.com/charge/alternatorwiring.htm
I was getting a light charge: 12.2 volts at idle, 12.7 volts at 2000 RPM, then dropped down to 12.2 again at full throttle.
In the process of troubleshooting, I noted the sense wire is only getting 9.3 volts (still not sure why... haven't figured it out yet)
So, using the troubleshooting in this guide: http://www.boatfix.com/merc/Servmanl/18/18C4R2.PDF on page 8, it says the SENSE wire should be getting 12 volts.
So I added a 5amp push/pull circuit breaker to give 12 volts to SENSE terminal (just added to existing terminal). VOILA!! It now charges at 14.5 volts! Perfect!!
We hit the river, and about ten minutes in, the engine quits for about 2 full seconds then picks up again (it has NEVER done that) and I look down to the volt meter.. 12.2 volts. Not charging anymore.
So here is my question:
Did *I* fry the alternator, or was it already on its way out? It's pretty new.
I don't want to spend $200 on a new alt just to have it be toast after 10 minutes again.
I was getting a light charge: 12.2 volts at idle, 12.7 volts at 2000 RPM, then dropped down to 12.2 again at full throttle.
In the process of troubleshooting, I noted the sense wire is only getting 9.3 volts (still not sure why... haven't figured it out yet)
So, using the troubleshooting in this guide: http://www.boatfix.com/merc/Servmanl/18/18C4R2.PDF on page 8, it says the SENSE wire should be getting 12 volts.
So I added a 5amp push/pull circuit breaker to give 12 volts to SENSE terminal (just added to existing terminal). VOILA!! It now charges at 14.5 volts! Perfect!!
We hit the river, and about ten minutes in, the engine quits for about 2 full seconds then picks up again (it has NEVER done that) and I look down to the volt meter.. 12.2 volts. Not charging anymore.
So here is my question:
Did *I* fry the alternator, or was it already on its way out? It's pretty new.
I don't want to spend $200 on a new alt just to have it be toast after 10 minutes again.