Tach is working and not working

[iggyw1]

My tach on my boat does not go to zero when my engine is off. The needle stays at about 2000 RPM. When I start the engine, it idles and the tach shows 800 RPMs, and it seems like the tach works good while the engine is running, goes up and down like it normally did in the past even at the highest RPM (5,500 max. at WOT), but when I shut the engine off, the needle sticks at about 2,000 RPM on the gage. Do I need to replace the tach? It is very difficult for me to get up under the dash or I would not hesitate to just change the tach.

 

[Chris1956]

A lot of tachometers stay at their last reading, when engine is shut off. They usually zero when key is switched on, but engine is not yet started. You might look up your tach on the OEM website and see what it is supposed to do.

 

[Davetowz]

Compare the running readings to a good quality automotive service tach, if they are pretty close, all is good. If the boat tach doesn't match, replace it.