1993 200 Merc Classic tach, how does it work?

[dynatrak201SS]

Hello,<br /><br />My tach does not seem to be accurate at mid to high RPMS. It seems OK at idle, and low speeds, say 750-2000 rpms. Above that it seems to stick sometimes, othertimes it just reads high, and inaccurate, like 5500rpm's at 30 MPH, 6000rpms at 50mph. Where does the gauge get its reading from? Where does the measurement come from? Is there anything I can do to verify it?<br /><br />Thanks,<br /><br />Chris

 

[The Marine Doctor]

Re: 1993 200 Merc Classic tach, how does it work?

The measurement comes off the stator,voltage regulator then to the tach.<br /><br />To test the regulator go here.<br /><br /> http://www.themarinedoctor.com/testarec.htm <br /><br />If this checks out ok it is likely the Tach or a connection somewhere.<br /><br />TMD