86' GT150 Stator or Rectifier/Regulator?

mak747

Cadet
Joined
Apr 27, 2009
Messages
11
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?
 

Will Bark

Lieutenant
Joined
Aug 1, 2010
Messages
1,470
Re: 86' GT150 Stator or Rectifier/Regulator?

On my 1987 Johnson 150 when the battery quit being charged and the tach operated erratically it turned out to be the rectifier/regulator which is located halfway under the flywheel; a pricey little repair but not bad at all once the flywheel is off. Others will chime in to do other tests to make sure that's what the trouble is. Good luck
 

emdsapmgr

Supreme Mariner
Joined
Dec 9, 2005
Messages
11,551
Re: 86' GT150 Stator or Rectifier/Regulator?

The tachs get their signal from the combination regulator/rectifier on that model. Will has some good comments. Tachs can act oddly when that rectifier/regulator starts to go. Your voltage readings should hold in the 13 to 13.5 volts, so at 12.3 volts it is probably not charging properly, so the rectifier/regulator is a prime suspect for replacement. The stator coils that provide recharge to the battery through the rectifier/regulator are separate from the ingition coils, so likely the engine quitting is probably not related to your charging/tach issue. Any change you have some trace water in the fuel?
 

mak747

Cadet
Joined
Apr 27, 2009
Messages
11
Re: 86' GT150 Stator or Rectifier/Regulator?

Will,

Thanks for the reply. I am going to try replacing the rectifier/regulator and see if that resolves my problem. You are right about getting the flywheel off, it was a bear. I took advice from other post on this forum and with the help from their suggestions I was successful in removing it without totally losing my sanity.

emdsapmgr,

I checked the clear bowl on my fuel/water separator filter and see no indication of water in the fuel. I am going to replace the rectifier/regulator and see if that resolves my issue.

My thanks to both of you for the information/suggestions.
 
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