Johnson Voltage Regulator

[chuck bartus]

I have a 1987 150HP Johnson with a 35 AMP voltage regulator that seems to to putting out over 18 volts at medium RPMs. Can't tell what the RPMs are as the tach is not working also. Before I replace the voltage reg. could someone tell me everything to check? I've checked the voltage at the battery and it matches the gage readings. I've also tightened the battery cables with no change. I have also checked the voltage at the gray wire at the tach and have 9 VDC which tells me the tach is bad. Physically the voltage reg. looks reasonably OK except for a few cracks on top of it. I was thinking of replacing the voltage reg with an aftermaret CDI unit. Any ideas would be helpful. Thanks.

 

[Barnacle_Bill]

Re: Johnson Voltage Regulator

Replace your rectifier/regulator. You are reading 9VDC at the tach because of shorted diode(s) in the rectifier. This will cause your no-charging and the tach not to work. The tach may be good. The tach works off AC pulses from the stator. The connection is made at the rectifier simply because it is a convenient place to do it,

 

[reload]

Re: Johnson Voltage Regulator

OP said it is overcharging at 18 volts. Still think the reg is bad.

 

[chuck bartus]

Re: Johnson Voltage Regulator

Yes. Perhaps I should have said the battery appears to be fully charged. It starts with plenty of power and runs all the usual electronics. My experienced OMC dealer is the one who said I should be getting 9 VDC at the gray tach wire, and should not be having 18 volts at the gage and VOM. So what do you suggest? Should I install another battery? Thanks again.

 

[tashasdaddy]

Re: Johnson Voltage Regulator

go to the engine faq forum, good post there.

 

[ezeke]

Re: Johnson Voltage Regulator

The point is that the regulator in your regulated rectifier is not functioning properly, which is sufficient reason to replace the assembly. Some of your other devices and many batteries may not tolerate 18 volts.