Control Interchange

[Polara Pat]

I have a '93 40 Merc 4 cylinder (serial # 00259417) on my boat that is officially screwed. A friend has offered me an older Merc 50 (serial # 7070083 which may be a Canadian stamping) The shift and throttle cables look like they may work from my '93 controls but the bulkhead is significantly different. Is there an adapter to mate the older motor to the new controls or am I looking for a complete set of controls to go with the old motor.

Keep in mind that I haven't even tested the older motor or figured out for sure what year it is. I think it may be a '76 but can't be sure.

Thanks, Pat

 

[Chris1956]

Re: Control Interchange

When you say bulkhead you mean wiring harness, right? The control cables (shift and throttle) should work fine. Steering and fuel should work fine. You will need to change fuel line quick-connect. Wiring can be adapted by grafting the old harness to the new or directly connecting it, bypassing the Mercury Quick disconnect plug.

 

[Polara Pat]

Re: Control Interchange

When you say bulkhead you mean wiring harness, right? The control cables (shift and throttle) should work fine. Steering and fuel should work fine. You will need to change fuel line quick-connect. Wiring can be adapted by grafting the old harness to the new or directly connecting it, bypassing the Mercury Quick disconnect plug.

Yes, I mean the wiring harness. The throttle and shift cables look like they should work. A wiring diagram for each harness would be amazing but I won't be holding my breath on that.

My local small engine guy is warning me off the '76 50 but I would like to at least see if it will fire up. It can't be worse than the other two duds I have laying on my shop floor.

 

[Chris1956]

Re: Control Interchange

The '76 should have the old wiring colors and the 40HP motor the new wiring colors. The wires will match in number and here are the color codes old motor followed by new motor. Battery power and ground wiring colors didn't change.

red-red: battery +12VDC; black-black: ground; white-purple: Ign accessory +12VDC; grey-yellow/black: choke; yellow-yellow/red: starter solenoid; salmon-black/yellow: Ign killer wire; brown-grey: tach signal;

 

[Polara Pat]

Re: Control Interchange

The '76 should have the old wiring colors and the 40HP motor the new wiring colors. The wires will match in number and here are the color codes old motor followed by new motor. Battery power and ground wiring colors didn't change.

red-red: battery +12VDC; black-black: ground; white-purple: Ign accessory +12VDC; grey-yellow/black: choke; yellow-yellow/red: starter solenoid; salmon-black/yellow: Ign killer wire; brown-grey: tach signal;

Thanks for this. I'll see if I can't make this work and try to salvage the last few weeks of boating.

Pat

 

[Polara Pat]

Re: Control Interchange

Sooo, does anyone sell an early style female plug that I can splice onto my '93 cable? The early style has four small pins and two fat pins on the motor side whereas the '93 plug is a male connector with eight small pins.

 

[Chris1956]

Re: Control Interchange

It is likely someone has that plug, but I do not know where you can lay your hands on it. The fat pins are for the battery cables. You can connect those directly. Negative to the frame ground bolt on the starboard side of the motor, +12VDC cable to the starter solenoid secondary post. The balance of the cables can be butt spliced.