Eractic tach

[Dogman525]

2005 f250 Yamaha. When running the tach sometimes just jumps up around 1000-1200 rpms and stays there for a lil while then it goes back to normal rpms. Engine stays the same not slowing or speeding up

[Dogman525]

Also this is an analog tach

[99yam40]

might try moving the setting switches around some.

maybe a bad connection inside the tach.
moving them back and forth may help clean the connection

[throrope]

More than nine of ten tach issues are connection problems and marine environments are rough on wires. Any one in the mix can give grief. The connections on the back side of the instrument are buggers to reach. Bad ground connections are often hard to find. Good luck.