86' GT150 Stator or Rectifier/Regulator?

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?

Look under the fly wheel and check the stator for puddled up plastic. That is a sign of the stator coil's insulation melting down. If it looks good an no puddles The VR would be suspect. When was the last time the water pump's impeller been replaced? How is the water pressure? Do you have wing nuts on the cranking battery? You'll have to pull the flywheel to replace the VR.

ChampioNman,

Thanks for the reply. The impeller was replaced last year and though I don’t have a water pressure gauge the tell-tell shows a strong steady stream. Battery has regular nuts on the posts and I check them regularly to ensure they are good and tight. I have pulled the flywheel and see one small drop of hardened black gunk under one of the coils at the rear of the stator. If the stator test good per the service manuals OHM test, do you still think that it could cause these symptoms?

I would lean toward the regulator.