02 Fisher w/ 60 HP Merc Bigfoot tach issues

wgl333

Petty Officer 2nd Class
Joined
Jan 11, 2011
Messages
140
Last night when out for a cruise, I bumped the throttle to about 15 MPH (by GPS) when suddenly the tach spun up from about 4900 to almost 6000...with no actual revving of the motor. Below 3000 RPM, I was getting an accurate reading when compared to MPH, but once the tach got near 5000, the readings were all over the place. Thoughts/input/insights?
 
Top