Installing ignition kill on 70's Magneto motor w/ mercontrol.

[Mpizzle]

Hey all,

Trying to install a kill switch on my 16' boat. I run a 650 Mercury from appx 1976 and a Mercontrol throttle forward control unit from appx the same time. I took the mercontrol box apart to get at the ignition in order to the wiring. Have a few questions about installation. This is the switch: http://www.go2marine.com/product.do?no=88562F&WT.mc_id=gb1 It has a black and a red wire coming from the back of it. I assume I am suppose to hook these two wires in circuit with my ignition.... but I don't know which wires to use from the ignition.

Here is the diagram for the mercontrol... ; http://www.maxrules.com/oldmercs/Wiring/1966ona/30.gif

I am assuming that I need to hook the switch up with one wire going to point D and one going to E, is this correct? Where should cuts be made to assure the proper circuit? This is a magneto system BTW.

 

[Laddies]

Re: Installing ignition kill on 70's Magneto motor w/ mercontrol.

That diagram is for a battery CD ignition. Is it the wrong diagram or did you misspeak yourself?

 

[Moody Blue]

Re: Installing ignition kill on 70's Magneto motor w/ mercontrol.

To install the kill switch to the circuit diagram you provided, you must cut power (+12V) to the switchbox to kill the engine. That would be the WHITE wire, terminal F.

In mine, I cut the white wire between the harness at the key switch terminal (F) inside the control box. Wired the kill switch between the harness and the ignition switch and ran the wires along side the tach connector wires then out the bottom of the housing and up to the dash where the kill switch is mounted. The kill switch must be normally open (NO) type. When the clip is installed, the switch closes, allowing +12v to pass to the switchbox. If the clip is removed, the circuit opens, disconnecting +12v from the switchbox and the ignition system is disabled.

Beware, the wire insulation is most likely brittle and will crumble and fall off the wires as soon as you try to move them. I ended up completely stripping all wiring out and replacing it all.

 

[Mpizzle]

Re: Installing ignition kill on 70's Magneto motor w/ mercontrol.

Thanks for the input. Surprisingly, the insulation and wiring is not brittle, everything is in pretty good shape.... just really greasy!

Thanks for the input but I am now confused on if I am using the right diagram due to the first post..... This is my motor:

Its an older Merc 650, pretty sure it is a 1976. Says "Thunderbolt Ignition" on the front of the case.

I went here for diagrams: http://www.maxrules.com/MERCwireindex.html Clicked on 650-850 thunderbolt and thats where I got that diagram.

I suppose there it could be the 3 cyl 650? But I dunno... help appreciated.
Already missed a beautiful weekend on the water because of this problem

Matt

 

[Laddies]

Re: Installing ignition kill on 70's Magneto motor w/ mercontrol.

If it's a 76 the engine has a distributer and is battery CD if it has 3 coils it is a 77 or newer and is ADI ignition let us know.

 

[Mpizzle]

Re: Installing ignition kill on 70's Magneto motor w/ mercontrol.

If it's a 76 the engine has a distributer and is battery CD if it has 3 coils it is a 77 or newer and is ADI ignition let us know.

There is a distributor obviously visible. What do you mean coils?

Sorry, I'm a newb with outboards.

I tried to find the serial number and go about it that way but I can't seem to find the plate with this info? Shouldn't it be somewhere on the transom plate on either side between the hull and the motor?

 

[Moody Blue]

Re: Installing ignition kill on 70's Magneto motor w/ mercontrol.

Two places for S/N. Should be a nameplate riveted to the transom clamp assy right above the tilt tube.

Another place to look is on the distributor housing frame up just under the flywheel. Locate the timing gear ontop of the distributor then directly below that should be a SN stamped into the frame.

As for the coil question, there were two types of ignition systems of that era. The older type used a distributor and a single ignition coil. The newer type used an electronic "distributor" and a separate ignition coil for each cylinder.

If you say there is a distributor obviously visible then you have the older type battery CD ignition system. The diagram you have is the correct one.

 

[Mpizzle]

Re: Installing ignition kill on 70's Magneto motor w/ mercontrol.

Hey what do you know I found the ser# 4139522, didn't find a direct match for the number on the chart, but did find the digits 413 starting for 1975. There is no riveted plate near the tube, I had to dig around behind some wiring and found it stamped to the frame.

 

[Mpizzle]

Re: Installing ignition kill on 70's Magneto motor w/ mercontrol.

I figured it all out and got it wired back together, Moody Blue was spot on with his description! Wired the switch between terminal F and the motor, plugged it into the hose and tested it out, worked just like it should! Thanks a million MB!

Now I can have a bit more piece of mind out on the bay in my small craft.

Matt