Mercruiser 3.0 (2001) RPM question

[Scoob1057]

I got my boat up and running!! I adjusted the idle speed to 700 rpms but the tach will jump around after running for 30 seconds. If I turn it off and restart the tach will work for a few seconds then jump from 700 to 3000 back and forth. What steps do I need to take to fix this?
Mercruiser 3.0 (2001) Alpha

 

[Don S]

Re: Mercruiser 3.0 (2001) RPM question

If the engine is running fine (no misses) you probably have a bad tach, and then you replace it.