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hooking up tachometer

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  • hooking up tachometer

    I replaced my Mercury 3 cyl outboard with a 4 cyl Johnson. Where do I hook up the sending wire for a tachometer? I have a side control unit mounted on my center console. I did switch my tach selector switch to the 4 cyl position already.

  • #2
    Re: hooking up tachometer

    Your tach's selector for a 2cycle is based on the number of poles on the alternator, not the number of cylinders (which matter for a four stroke). A Johnson 4 cyl should have 12 poles and uses the "6p" setting on a Teleflex tach. you need to give more info about the motor for someone to find the send wire for you.


    • #3
      Re: hooking up tachometer

      thanks for the reply Dave. I goofed though, the motor is an 1986 Evinrude 110 VRO. Will I need to run a wire from the motor or is there a hookup on the control unit?


      • #4
        Re: hooking up tachometer

        If I remember right , the remote control for that vintage had the alt. tach wire in the acc. plug on the control. I believe there is three wires in the plug. One was ground, the middle was tach and the other was acc. A voltmeter will tell you which is which. Be dam sure the tach is compatible. ...check the manual to be sure on the wiring!!
        Alias "schematic"


        • #5
          Re: hooking up tachometer

          How do I find out if tach is compatible? was a 1990 mercury 90 hp 3 cylinder


          • #6
            Re: hooking up tachometer

            yo...BKooL68. Get the make and model of your tach and research it. Don't hook it up until you know what you have. Some tach's are for ignition primary, some connect directly to charge coil, and some to the rec./reg. assmy. If you have tilt'n trim I believe you have a rectifier/regulator assmy. The tach signal comes out of this unit, so don't hook anything to the 'tach connector' unless you're sure its the right tach. If you want to take a chance on a no-name or universal tach, I'd run a new wire and connect it directly to the alternator charge coil. (no chance of damaging the rec./reg. assmy.) I don't recommend this unless you are electronically inclined and understand whats going on. Get a manual. (although I don't remember seeing much documentation on this)research is the key!!
            Alias "schematic"