Merc 40 hp. Won't turn off

[fireman57]

Been on the Johnson/Evinrude forum for years. Never had to deal with a Merc until now. Have a 40hp not sure of model number but has 402 on the upper lower unit cover. When first hooked it up it ran great and shut off. Now it just runs great. Have to unhook fuel and let it run out. Took control box apart and ignition switch looks okay. Like I said it turned off the first three or four times I ran it. Guessing there is black/yellow wire on the engine somewhere to track down. Any gurus ant to save me some time and head me in the right direction? Thanks in advance.

 

[wrench 3]

It's going to be a little vague without a year, serial number or something, but here goes. You also need a good ground to the ignition switch as well. It connects the black/yellow wire and the black wire together to kill the ignition. This is assuming that you have magneto ignition and a round harness plug to the engine.
The black/yellow wire goes to the switch box on the engine. It's probably behind a plastic cover on the starboard side of the engine.

 

[fireman57]

That is the system this engine has, the plug on the side of the engine. I guess I will pull up a breakdown and see what you guys call a switchbox. Thanks again. Should have this fixed tomorrow. Still a great site after all these years.

 

[Mohawkmtrs]

Mercury's Switchbox = OMC's Powerpack

 

[GA_Boater]

Until you figure out what's not allowing the motor to be shut off, temporarily using the choke will stop the motor. Press the choke button or push the key in before switching the key off.

 

[wrench 3]

The Mercury switchbox in automotive terms is an ignition module.

 

[fireman57]

Thanks again guys. Holding the choke button in would not kill it. Turned out ignition switch was not making contact with the kill wire. Problem solved. Again, thanks!