1979 Mercury 115 HP Outboard - Shut-off Wiring

[Challenger440]

I just finished a re-wiring project on my 1979 Mercury 115 hp motor. The ignition switch is a exact part # replacement, the wiring has all been replaced on both sides of the plug and in the engine. I started the engine today, and it runs fantastic -- but to my surprise when I turned the key to shut the motor off, it continued to run.

What could be the cause of the engine not shutting down? What wire do I need to put a kill switch style toggle on, or what is the best way to fix this problem? The only way I was able to get the engine to stop running today was to pull the fuel line. Obviously I will need to figure out a better way to turn the engine off.

Any help at all would be GREATLY appreciated. Today has really left me scratching my head on this. A few weeks ago who would have thought that my problem would be to get the engine to Stop running instead of Start running!?

Thanks again!

 

[Challenger440]

Re: 1979 Mercury 115 HP Outboard - Shut-off Wiring

I have gathered a bit more information on this problem. My engine has the two ignition packs. I talked with a guy that said that if you can ground out the brown wire (as shown in the attached wiring diagram) that connects to the rectifier then that will kill the engine.

My problem is, I still don't know what the industry standard is, or how this can be accomplished. Can I simply put a toggle switch on that brown wire, so that when is engaged it will ground it out?

Or is my problem just in the way I have my switch wired?

If somebody could take a look at this attached wiring diagram and give me a little insight it would be greatly appreciated.

Thanks again!

 

[Big flop]

Re: 1979 Mercury 115 HP Outboard - Shut-off Wiring

The orange wire that hooks to the
switch box's, (packs) gets grounded
when the key is turned off.
When the orange wire is grounded,
no spark.
later model kill wire is black/yellow stripe.

 

[Quad82]

Re: 1979 Mercury 115 HP Outboard - Shut-off Wiring

Maybe you have the hot wire from +12 on your new keyswitch reversed. My 78 Merc 115 has 5 lugs on the switch. A(red), E(orange), D(black), B(yellow), F(white). Off = D E. Run = A F. Start = A F B. I have a color wiring diagram that I copied off this site on 6-29-2010. I can not find the thread. But if no one chimes in with it, I can fax you a copy. I keep it in my boat incase of a problem while out on the water. Darrell

 

[Challenger440]

Re: 1979 Mercury 115 HP Outboard - Shut-off Wiring

Thanks for the reply's. I am still trying to chase down the issue and not having much luck. I checked the connection at the switch, and my orange wire is connected to terminal E on the switch. When I check the connection I get connectivity from the negative terminal to the orange wire when the switch is off, but not when the switch is on -- which is how it should be. I believe. I went back to the back plug and checked and get the same result - when the key is on the orange wire is not grounded - when the key is off the orange wire is grounded. Now, inside the engine this same orange wire should connect to the ignition packs right? And those two wires (one to each pack) is where that orange wire when the switch is hit will ground them and stop the engine? All this is wired up correctly but when the engine is running, and I turn the key off the engine still does not stop.

Can anyone shed some light on how this could happen? And if there is not a logical reason or way to fix it -- is there a way to bypass the original equipment and install a kill switch to the engine?

Thanks again for your time!

 

[bktheking]

Re: 1979 Mercury 115 HP Outboard - Shut-off Wiring

Disconnect the orange wire at the switchboxes and verify ground on both.