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18 HP Mercury switch box testing...

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  • 18 HP Mercury switch box testing...

    It's a 1981 18HP (serial# 5905478) with starter button on the tiller. I'm getting no voltage to the ignition coils. The stator and trigger coil all ohm out within the manual's specifications. Is it possible to test the switch box (power pack) with a meter to check if it's OK? The motor was running fine, then just died and wouldn't even think of firing. I had a nice long paddle back to the ramp.Thanks for any help!!WillCoastal Georgia


  • #2
    Re: 18 HP Mercury switch box testing...

    Did you disconnect the blk/yellow at the switch box to make sure it was not a switch problem? Then ck for voltage from the stator and trigger if you have both it must be the box

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    • #3
      Re: 18 HP Mercury switch box testing...

      Thanks Laddie. I was hoping it was just a bad kill switch so I did disconect the kill switch's black/yellow lead and still nothing to the coils. I'll double check. What voltage should I be getting out of the stator and the trigger coils? Dumb question, but should I set my meter to AC or DC to check the stator/trigger output voltage?Thanks!Will

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      • #4
        Re: 18 HP Mercury switch box testing...

        Make sure your ground on the switch box is clean and tight stator/trigger tests are ohem checked on the R 100 scale of meter set on ohems ;with your start key turned off
        You forget you don't remember!
        Friends are family we choose for ourselfs
        Ifin YOU KNOW it goes....if not it doesn't
        Transom Repair http://www.shareaproject.com/pages/i...i,1437,00.html

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        • #5
          Re: 18 HP Mercury switch box testing...

          Does this model of 18HP Mercury have a mercury switch? What is the function of the Mercury switch? To interrupt the ignition when the motor is tilted out of the water? When it was running, this motor didn't shut down when tilted out of the water. The Clymers manual shows a vague picture of the location but I can't locate a "mercury switch" on this motor. Does it even have one?Thanks!WillCoastal Georgia

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          • #6
            Re: 18 HP Mercury switch box testing...

            I think they were on only tilt and trim models. I've got one in the boat house(18hp merc) I'll go check for a switch but i don't think it has one.

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            • #7
              Re: 18 HP Mercury switch box testing...

              nope only a switch box. mine is a early 80s

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              • #8
                Re: 18 HP Mercury switch box testing...

                Willy the trigger spec is 5volts, the stator high speed is 20v and the low speed is 180v you will need a DVA to read them I belive

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                • #9
                  Re: 18 HP Mercury switch box testing...

                  I see that a DVA is needed to measure the voltage coming from the stator and trigger. My Fluke meter has a max/min/average feature. I'm guessing this will do the same thing (I hope...)?Thanks for all of the help! I also found http://outboardparts.com/mercury/tro...shooting10.htm to have some great info. about trouble shooting OBs.Thanks!Will

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                  • #10
                    Re: 18 HP Mercury switch box testing...

                    I don't know Willy, but I got a DVA adapter for my Fluke meter from Rapair ---Bob

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                    • #11
                      Re: 18 HP Mercury switch box testing...

                      I'dd like to know how you volt test without it running Hummm
                      You forget you don't remember!
                      Friends are family we choose for ourselfs
                      Ifin YOU KNOW it goes....if not it doesn't
                      Transom Repair http://www.shareaproject.com/pages/i...i,1437,00.html

                      Comment



                      • #12
                        Re: 18 HP Mercury switch box testing...

                        you pull the cord

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                        • #13
                          Re: 18 HP Mercury switch box testing...

                          Or push the starter button Thanks,Will

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                          • #14
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                            Re: 18 HP Mercury switch box testing...

                            That's a pretty good arm you got testing high speed volts and I need one of those starters
                            You forget you don't remember!
                            Friends are family we choose for ourselfs
                            Ifin YOU KNOW it goes....if not it doesn't
                            Transom Repair http://www.shareaproject.com/pages/i...i,1437,00.html

                            Comment


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