Mercury 5.7L v8 with Alpha One Drive / How do I troubleshoot my tach?

[rickstuntebeck]

I have 1997 Sea Ray 210 BR (open bow).

It has 5.7L v8 (210) HP engine.

I have the factory 14.25 x 21 degree pitch aluminum prop.

The tach shows 5500 RPMs with 3/4 throttle.

I am thinking about replacing the tach.

I had it tested by a mechanic and he says when he tapps it the tach gauge
goes up and down. SO it does not show correctly.

How do I replace it?

How much does a 6000 RPM tach cost?

Please advise,

Thanks,

Skipper Rick.
Mpls MN

[QC]

Hey rick. I moved this to our Electrical section. Tachs are sort of universal to all engines. Before I do anything I would check the switch on the back and make sure it is set for a V8. If I had to replace it I would try and find the same Tach so that it matched my pother gauges.