1988 Merc 60 wont shut off

[AEROCOOK]

I fired up my 1988 Merc 60hp today and I couldnt get it to turn back off.
I turned the key off and removed it but it kept on running. I turned off the toggle switch below the key and it had no effect, the motor kept running.
The motor is not on a boat, it's on a stand in my garage. The motor was in storage for 2 years and it didnt have this problem when I last used it. As far as I can see, all the wires are hooked up properly but maybe I missed something?
Can anyone offer some advice?

 

[Laddies]

Re: 1988 Merc 60 wont shut off

It sounds like the ground wire to the box and switch is unhooked, here's a wiring diagram and you can see the black wire connects at the solinaid ground if it's hooked up then it probably has come unplugged in the box, eldom does the harness get damaged enough to cause a problem. You might check the male posts on the engine harness to see the black or black/yellow aren't bent.

 

[AEROCOOK]

Re: 1988 Merc 60 wont shut off

Thanks Laddies.
I cant see a harness image in your post.

 

[AEROCOOK]

Re: 1988 Merc 60 wont shut off

Update... I looked for disconnected wires under the hood and found none. Took the control box apart and there were no disconnected wires there either. Tried running the motor again and this time the starter motor wouldnt turn off, the bendix disengaged but the motor kept turning. I disconnected the negative battery cable to stop the starter and when I reconnected it the starter did not start turning again. Tried starting the motor again and it fired right up but it still will not turn off. Im beginning to suspect the ignition switch it bad. Are these somewhat prone to failure?

 

[AEROCOOK]

Re: 1988 Merc 60 wont shut off

Could a bad rectifier cause this condition?
Im running out of ideas.

 

[Laddies]

Re: 1988 Merc 60 wont shut off

Sorry I missed your post ,yes it could be a ignition switch here's a test for your switch.

 

[AEROCOOK]

Re: 1988 Merc 60 wont shut off

Laddies.
thanks so much for getting back to me. I will test the switch in the morning and post the results.
One other question I had is whether the wire colors and their positions remain the same on both sides of the main plug connector i.e. black/yellow goes to black/yellow etc?
The reason I ask is because mine dont seem to.

 

[AEROCOOK]

Re: 1988 Merc 60 wont shut off

Just completed the test and the switch is good.
I have a vague recollection of an accidental short to ground when the motor was being removing from the boat, the bone head (me) removing the motor forgot to disconnect the battery before starting and I got an arc while swinging a wrench. I suppose it's possible that I fried somthing.
Any idea where to look next?

 

[Laddies]

Re: 1988 Merc 60 wont shut off

Go to the switch box and unplug the black/yellow wire then start the engine when you ground the black/yellow wire the engine should stop, if it does the problem is in the harness go to the switch unplug the black/yellow and ground it to the box it should quit if it don't run a wire to the engine ground if that kills it then the black/yellow is good and the problem is in the ground if it don't kill it then the problem is in the black/yellow. where ever it is I would suspect the engine plug some times the wires break or come unsoldered, if thats the problem you don't have to replace the harness just open the harness near the plug and install a short jumper around the plug on the bad circuit and tape it to the harness.

 

[AEROCOOK]

Re: 1988 Merc 60 wont shut off

Solved.
Just as you had suggested Laddies, there was an open circuit with the black/yellow wire right at the plug. routed a jumper wire around the plug and all is well.
Thanks a million for the help.