erratic tachometer

[cbay]

[on the spring shake down run] the multifunction tach for my 2001 HPDI 200hp (z200txrz) is giving very erratic tach readings, while the other function seem to be fine. what can I do myself short of calling for the traveling tech from the local dealer.

[boats.net]

Other than loose or bad connection on wires it would have to be checked with a voltmeter.

[cbay]

The Boats.net parts number for my tach is not the same as the Yamaha #....are these Yamaha tachs or compatable tachs by another manufacturer?