tach reads double rpm on150 vmax

[gchan011253]

my tach just started reading double the approx. rpms. and also my volt meter is reading 15.5 volts about 2 volts higher than it was any suggestions. its an 02 150 vmax.

[boats.net]

Sounds like a bad tach. There is no calibration adjustments for voltmeter, the only thing you can do is replace it.

[ctbeacher]

Sometimes a bad voltage regulator/rectifier can cause a tach to give flunky readings. But they usually go all over the place. Any chance you can sub in a known good tach?

I think normal charging voltage is around 14.4 volts.

Also, does the voltage start out that high or does it climb from 13 or so? If it climbs and then the tach goes lunky, then I would suspect the voltage regulator/rectifier. Testing instructions are in the Secor repair manual.

Good luck.