40HP Johnson won't shut off

[dwagner]

1991 40 HP Johnson on a pontoon boat.
less than 2 months ago the ignition switch would not turn off the motor. Replaced the switch and now it has happened again. Could another switch be bad already or is there something in the motor that won't allow the motor to turn off even though the switch is in the off position?

[Rebel Sympathy]

The way your motor is stopped is: when the switch is turned to "off" it closes a circuit which shorts out the ignition. This circuit goes through the power pack. Since it is happening again, there is an excellent chance your power pack is the problem. Like many problems with power packs, it can be an intermittent one - working fine sometimes and not working properly at other times. Also, there could be a broken wire (the shorting circuit wire) somewhere in the harness. And, of course, it is possible your new switch is bad.