Out of control RPMs

[poengine33]

Any idea what would cause a 150hp yamaha Rpms to go out of control even after the key is turned of

[WET-BOX-MARINE]

bad tach will do it

[rodbolt17]

depends on the model number.
I know over the last 20 years at least 9 models of the V6 150 have been imported to the US market.