High reading tach and low Volt gauge.

[mtpocketsad]

Have a 94 SeaRay 230DA with the 5.0 L. Boat has sat for a year and half before I got it this fall. The tach reads around 1000 to 1250 to high at times, Not always. I have checked with inductive tach hooked to spark plug. Today for half the cruise it was high, and coming back OK. What gives? Other problem is the volt gauge doesn't get past 12.5. I checked with battery tester and it is charging. DO these gauges go bad or is there a wiring problem?

 

[Hampton]

These tachs are used for 4, 6, and 8 cyl engines. There is a switch on the back. Due to lack of cycling (the switch), it can become coroded. When it does, it may be trying to give readings for 6 or 4 cyl engines. Every 8 sparks will indicate 1.3 times as much in the 6 cyl position as it should on a V-8.

Solution: Loosen Tach, slide out, cycle switch several times to break corossion free. Set to 8 cyl., re-install.

If you don't have a 4, 6, 8 switch on the back, then, nevermind.