Home Forum Ask A Member 3.6 HP Mercury carb questions

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  • #243384
    outbdnut2
    Participant

      US Member - 1 Year (includes $3 online payment fee)

      Yes – I noticed yesterday when I was replacing gas lines that the tank outlet was about 3 inches lower than the carb input. On a hot day if you run low on fuel, maybe you could idle off the lake by shutting the tank vent and letting the heat of the sun soaked up by the black motor give the gas enough vapor pressure to get some into the carb!!??….may work better with the cover off and the sun directly on the black tank!
      Dave

      #243442
      outbdnut2
      Participant

        US Member - 1 Year (includes $3 online payment fee)

        Success! I’ve got this little thing running! After much frustration with the sticking choke, and another half dozen issues with the carb, and a spray can shot of oil to the base of the spark advance magneto pivot base to make the throttle move without needing two hands. It didn’t want to fire at all at first, but a small shot of starting spray into the spark plug hole (that way it doesn’t wash lube out of the crankcase) it fired briefly. Two more tries at the starting fluid directly into the cylinder and it stayed running long enough to adjust the carb and now it runs good. The only thing left is to make a new carb bowl gasket – I hoped the old one would work, but it leaks. The gearcase was empty – no oil or water – don’t know if it leaked or was drained, but it doesn’t appear to be leaking now.

        Thanks again Bill for the carb info!

        I hope I never see another one of these again!
        Dave

        #243449
        crosbyman
        Participant

          Canada Member - 2 Years

          patience brings joy… thanks for the feedback …on a happy ending 🙂

          Joining AOMCI has priviledges 🙂

          #243450
          crosbyman
          Participant

            Canada Member - 2 Years

            patience brings joy… thanks for the feedback …on a happy ending 🙂 you are now our AOMCI Merc 3.6 carb S.M.E. congrats

            Joining AOMCI has priviledges 🙂

            #243469
            billw
            Participant

              US Member - 2 Years

              I bet it runs pretty good, doesn’t it? Those weren’t bad power heads.

              Long live American manufacturing!

              #243491
              outbdnut2
              Participant

                US Member - 1 Year (includes $3 online payment fee)

                Yes Bill, it does run amazingly good. It is a bit hard to start when cold – I think I have to make a new gasket between the carb and the engine. It may be leaking around the edge on top by the port where the “choke” gas gets pulled in. First I’m going to put it on a boat today and get the high speed jet set right and see if that helps cold starting. I talked to the owner yesterday and he said he’s going to sell it – that’s good because it means I’ll never have to work on it again!
                Dave

                #243730
                outbdnut2
                Participant

                  US Member - 1 Year (includes $3 online payment fee)

                  FYI: I learned some more things about the carb that I’m mentioning in case any of you ever have the misfortune of having to work on one of these:

                  1. The choke (which is a small piston that moves to open or close a small port to the carb bowl gas) will not work unless the throttle piston (yes a vertical piston in the carb throat instead of a butterfly valve) is at minimum setting – and the word “start” on the case opening by the throttle lever puts it there. If the throttle is open farther, there is not enough suction at the choke gas port to draw gas through the choke-piston port. So the throttle has to be near minimum or you will pull and pull and pull on a cold motor!

                  2. The link from the carb throttle to the motor’s throttle lever (the vertical threaded rod out the top of the carb) has to be adjusted so the piston in the carb throat just gets to the top of the throat (max open) at WOT, and not a bit farther. First time I put it on a boat and went to WOT, the throttle piston went up a bit too far and jammed, and, although the motor slowed down some with the throttle lever, that was due to retarding the spark, and not backing off the carb throttle. Adjusting so it just barely gets to the top of the carb throat at WOT cured that problem.

                  3. It has high and slow speed, spring-loaded to keep in place, mixture screws; but the high speed screw appears to be no more than a jet that adds a slight bit of fuel to that already provided by a fixed jet that hangs in the carb bowl, so you can turn that adjustment several turns, including all the way in (lean-off) and the motor still runs pretty good. It was subtle, but between 2 and 4 turns out, it did run slightly faster. The slow speed mixture screw was similarly not very responsive either, but if it got adjusted too lean, it did eventually cough at idle. On the good side of all this is the fact that the motor ran pretty good at just about any setting of those mixture screws.

                  Now that I’ve learned a bit about this motor, I hope I never see one again!
                  Dave

                  #246385
                  gunni
                  Participant

                    hey outbdnut2, i have the same outboard, 3.6 merc, s/n 5802402 any luck finding the float pin and spring in your searches, unfortunately mine are gone,

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