Intermittent Tachometer

[waterlogged]

Our tach seems to be VERY intermittent.  Most times it doesn't work at all.  Suspect a loose wire but don't have a clue on where to begin looking - we are no mechanics here.  Anyone have any suggestions?

 

Should have stated it is a 90 h.p. Johnson outboard

Edited June 17, 2013 by waterlogged

[Don Supon]

The tach should be connected to the motor and to a power source.

 

Check the wires connected to the back of the tach. Look for broken, cracked , loose connections at both ends of these wires. Clean all connectors, as there may be corrosion blocking current. If all looks good, the tach itself may have an internal malfunction. Don't know how to test that.

[G-Daddy]

With a Johnson it could also be a bad rectifier.  If you have ever overheated, you might have smoked the rectifier.  That can also cause the symptoms you describe.  Unfortunately, you will probably find the rectifier is under the flywheel.  It's been a long time since I changed mine,  but if you find that is the problem - remember patience is a virtue.