1986 Johnson GT150. 35 amp stator. Water cooled rectifier/regulator. Went to the lake this weekend and noticed that the battery was not being charged by the motor. The voltage read 12.3 volts whether the motor was on or off. The voltage normally reads above 13v when the motor is running. When running down the lake the tach seemed to be working normally until I got to about 4500 rpm and then it jumped to 6500. I backed off a little on the gas and it went back down to 4500. It seems to work properly up all the way up to 4500 rpm and then just jumps way up. Also on the way back to the ramp I was traveling along at around 4000 rpm and the motor shut off like someone had turned the key off. It started right back up and ran normally the rest of the way back in. I checked the stator per the service manual and it tested good per the ohm's reading test. Could these symptoms all be related to a bad rectifier/regulator or is it most likely the stator or both?

Reg/rect won't shut down a motor unless it shorts out to the ignition box and that's pretty unlikely. The stator is fine, but the irratice tach movement indiacates the reg is going out. Or (if I'm not mistaken) That model may be hooked into the VRO and the VRO is shorting out.

Thanks for the reply Mike I think I will go with replacing the rectifier/regulator.