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New here and new boat owner 35hp 2 stroke

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  • New here and new boat owner 35hp 2 stroke

    Hi everyone. Long time fisherman and first time boat owner. My uncle has passed down his boat to me as he hasn't used it in over 10 years.

    I drained the gear oil, replaced the spark plugs, replaced the prop, replaced the main oil, new gas filters etc.

    Hooked the muffs up to the outboard and cranked her over and was able to get her to fire.. I had to adjust the idle screw a tad as it wanted to stall out. Now she only dies every once in a while when going from neutral to forward or reverse. I adjusted the screw that links all 3 carbs and allows the engine to rev so it will stay running.

    Road the boat for about 2 hours yesterday and she did well and then the outboard started feeling sluggish. It would all of a sudden get power again and then slug again so I trailered her home. Acted almost like it was flooding. Pulled the cowl and sure enough fuel is spitting out the top of the outboard.

    Fellow at the lake said possible bad gasket causing the flooding issue.

    Not sure on the year of the outboard. I just know when she isn't flooding she runs real well!

    Hoping someone here can point me in the right direction.

  • #2
    there should be stickers/ID tags on the mounting bracket giving model and serial and date of made.
    I guess this is a Yamaha
    how many cylinders?
    how many carbs?
    where is the fuel coming out of?
    top of outboard is a flywheel, and no fuel should be there

    but if it is at the top of a carb, a carb will not flood because of a gasket that I know of.
    possibly float is not closing off the needle and seat properly when the bowl is full.
    trash getting in and stopping the needle from seating would be my guess.
    take apart carbs and clean the whole fuel system
    dried residue from the lines and fuel pump possibly.

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    • #3
      Took a quick video explaining what I did and what I saw.. https://youtu.be/XrTzO_fBdhI

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      • #4
        1986 40 hp

        Not sure why you call it a 35

        as I said carbs and the rest of fuel system needs to be cleaned well and set according to specs in service manual

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        • #5
          Thanks I will pull all three carbs, clean and inspect and go from there.

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          • #6
            OK, pulled the air filter off and there was oil residue sitting by the flapper. I then pulled all 3 plugs and the bottom 2 look great the top one looked really wet and rich. Am I able to pull a single carb at a time? Looking at it it seems like I have to take all 3 off at the same time first by opening up the case in the back. Pretty odd they don't have a few screws or bolts to simply remove a carb. Even in my motorcycle triple you could remove one at a time.

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            • #7
              Disregard. I had to hit it with a rubber mallet much harder than I thought to break it free from the gasket.

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              • #8
                OK. All the carbs were gunked up. Floats work as they should. Got it running and it does run better, but has a miss/backfire through the prop on initial startup.

                https://i.postimg.cc/dtw46zHH/20210720-104847.jpg

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                • #9
                  heated sonic cleaner may be needed to clean all of the passages properly,
                  looks like water was in there from all of the rust

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                  • #10
                    Air in the fuel line to the tank. Buying a new tank and fuel line now.

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                    • #11
                      OK, she purrs now. Going to take her to the lake in an hour. Hopefully that cured it.

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                      • #12
                        I really do not see how air in line from the tank could cause the missing/backfiring thru the prop since pumping the bulb to prime before starting should have filled the carb bowls, so it should have run OK for a while

                        but I hope you got it running properly with no more problems

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                        • #13
                          OK, so the bulb is now firm as can be. I could pump the bulb 10-12 times before and it never got hard and I just heard air sucking before. New fuel lines tank etc and pump it twice to prime and it's solid. Took it to the lake and it wouldn't stay idling. Ran super rich. Finally got it to idle with the Rev deal down on the handle and quickly put it into forward. I was able to go down the lake but very slowly. Full throttle and it just felt like a dog. Decided to dock the boat and call it a night as the kid was squaking at me. I could smell fuel when I got it docked. Running super rich. My guess is my uncle compensated on the engine side to richen everything up because the fuel tank and fuel line weren't getting as much fuel as it was supposed to. Thus making It run really rich now that I have fixed the fuel delivery issue. I verified with an inline spark tester that all 3 coils are working properly.

                          Is there a manual for this thing? If I can't find a manual I'm just gonna call around and pay someone to tune it. I know it was a great running motor at one point.

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                          • #14
                            Im about to pull the carbs again and clean again. I plan to turn the screw in all the way on each carb. Write down how many turns in i had to go on each carb. I then planned to back them out 2 turns as a base starting point.

                            Motor doesn't want to stay running.

                            New fuel tank
                            New fuel lines
                            New fuel primer bulb
                            New battery
                            New oil
                            New gear oil
                            New prop
                            Cleaned carbs
                            Cleaned out fuel filter

                            Smells like it's running rich. Any ideas? Could a ripped fuel pump diaphragm cause fuel to be dumped into crankcase? I haven't checked the fuel pump yet.

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                            • #15
                              yes a leaking pump would put fuel into one crankcase that was furnishing the pulse for the pump but not all of them.

                              sounds like you did not even clean the pilot passages if you did not remove the screws last time you cleaned the carbs
                              it all needs to come apart and be cleaned.
                              with the rust you showed , no telling what all could be a problem.
                              I looks like it has a choke and not prime start, so at least make sure the choke is opened all the way when running
                              Last edited by 99yam40; 4 days ago.

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