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Thread: Starting a new 15 Yamaha 4 Stroke ?

  1. #1
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    Default Starting a new 15 Yamaha 4 Stroke ?

    I bought a new Yamaha 15 4 stroke for my HB21 this spring. When I take the boat out ... I put the throttle on start and squeeze the gas bulb and give her a couple pulls.... It fires and then stalls. I repeat this up to 5-6 times...... Even try to throttle it but it stalls out. But eventually we get underway.. Anybody have this experience or is this something that can be fixed at the dealer?? Thanks

  2. #2

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    You don't mention the choke. I'm not acquainted with the 15, but the symptoms sound as though it needs a little choke while it's warming up.

    To verify that thought, over the course of the day does it also stall out any time you restart it, or is it just a start-of-the day event? Both of my 2-stroke Yami's behave as you describe at the start of the day and require somewhere between half- and quarter-choke, but never again for the rest of the day. My 4-stroke 50 started doing that, requiring a little throttle help during warmup after about 150 hours with a whole lot of trolling, but changing spark plugs fixed it. I have a 6hp 4-stroke Yami, but haven't run it enough to say.

  3. #3
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    No choke on this one ,they say it's like starting your car( a newer One ). But once she stays running she is good for the day, restarts are just a little tug on the rope and never misses a beat all day trolling.

  4. #4
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    yes you have choke problems you nee to talk to a dealer to find out how to adj it [richen it up some ] there is a choke it is just not easy to get to
    { factory ADJ }

  5. #5
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    check out Yamaha outboard motor forum under chokes lot of info also they do work with you a lot let us know how it comes out ,
    the choke is an electric one on the electric start units I thint the 9.9 HP is the same one shoot me a PM if you can't find what I am talking about

  6. #6
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    This motor uses an enrichment system called Prime Start. There is an additional fuel passage that allows more fuel into the mixture for cold starts. After about 5 minutes of run time this passage is closed by a needle valve that is actuated by the charge coil voltage going through a heating coil. So it is not a choke as it does not restrict air like a choke plate, but it does increase the fuel to air mixture, similar result. Your issue is most likely that either the idle speed is too low or that the air/fuel mixture on the carb needs to be richer. The problem is that the EPA tells dealers that they are not supposed to touch the mixture screw and it is covered by a pressed in plug.
    Don't twist the throttle, this only adds more air during a cold start. The motor may need a re-start or two, but once it gets a little warm you should be good to go. Otherwise, your dealer may be willing to adjust your carb for you, should be a simple enrichment and you're on your way.
    Casey
    Yamaha Dealer
    Petersburg, AK

  7. #7
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    Excuse, that I interfere, but it is necessary for me little bit more information.

  8. #8
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    with what is said an the yamaha FORUM it shoild do it all look around on the forum about chock

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