Mercruiser 5.0 tachometer trouble

[shawns99]

My tach is not reading right. Sometimes it seems to get close but most of the time it is about 1500 rpm to high. What could be wrong?

 

[despy]

First, make sure the switch on the back is set to v8 setting. If it is, then all you can do is clean up all the electrical connections and if that doesn`t cure the problem, might be time for a new tach.

 

[chiefalen]

Cycle the switch on the back of the tach a few times and then set it to 8 cyl.

Now run the motor. Verify with a shop tach.

 

[WoodieMan]

Ditto Chief, those usually corrode internally. Make sure connections on the back of the gauge are nice and tight. Lastly, may also be a bad connection at coil or engine harness plug.