Wacky tach on my 1990 150 Johnson.....

[mopargreg]

This weekend my tach started not working on accell, when I bring the boat down to idle, most of the time, it works then when it starts to get over about 1500rpm it drops to 0, motor runs great , all electronics seem to be work good, but my volt meter reads about 10.5-12 volts but NEVER over 12, can the voltage regulator cause this problem on a 1990 150 Johnson? All my gauges are new Teleflex and I rechecked all the wiring.... My main concern is the tach, of course I don't want a dead battery either but it seems to be OK....

[GoneFission]

The tach on many 2 strokes reads off the stator.  If  you are getting no reading, you probably are not charging - interesting that the motor would not also be missing or performing badly...

Could be a rectifier or voltage regulator; your voltage should be over 13 volts when the engine is running and the battery is charged.  

Hope this helps - good luck!

[John Jones]

My '93 225 Johnson was doing the same thing and it was the regulator.  It depends on battery condition and load but I made several trips before it got so low it would not start.