motor won't turn off

[jwade]

Have a 03' 190 Bay with a 150hp Yamaha Vmax. Took it out the other night, cranked right up as usual but then when I arrived at my fish spot the motor stayed on even after turning the switch off. After 20 seconds of playing with the switch it finally turned off. When leaving, the motor once again cranked right up and upon arriving at the boat ramp the motor again would not turn off. I tried playing with the switch, removing/fiddling with the lanyard, turning the batteries off, and then repeating 10 times. All of the electronics would turn off when I turned the switch off, but the motor stayed at a perfect idle. Finally after about 10 minutes of trying different things it decided to turn off.

Any educated guesses as to what could cause a motor to stay on despite disconnecting the kill switch and turning off the ignition? Talked to a mechanic and he stated that it was either a bad ignition switch or "field mice had eaten through and shorted some wires". My limited familiarity with the wiring on the switch makes me wonder if the switch was bad, then why was it able to turn off the electronics but not the motor....and even then why did the kill switch not work.

Any help?

[Mud Runner]

When you turn the switch off, you cut power to the electronics. At the same time when you turn it off, it grounds the ignition circuit to kill the engine. The landyard does the same thing. You should also be able to kill the engine by pushing in on the red button with the lanyard in place.

[jwade]

For some reason its as if the engine has a mind of its own and neither the lanyard or ignition switches seem to have an impact on turning off the motor although they both are obviously used/needed to turn on the engine. Perhaps some kind of short has occured...may have to unfortunately leave this one to the electrical techs.