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Results 1 to 6 of 6
  1. #1

    Default 1998 Yamaha 40 hp problem

    Hello I am here on behalf of my brother. He is not real good with posting questions in the forums and such, so I am posting this for him in the hopes I may help. He has a 1998 yamaha 40 hp outboard motor and has been having some problems. The motor starts fine and idles terrific, once the boat gets going and he accelerates to full speed he is good for about 2 mins and then the motor begind to slow down gradually untill it is almost stopped moving. The only thing that works is to shut the engine off and then start it up again and do it all over. Any ideas guys or advice would be great. I can get more specifics on the engine if needed. Thanks in advance

    shaughnny

  2. #2
    Join Date
    Jun 2010
    Location
    Milton, Fl
    Posts
    546

    Default Re: 1998 Yamaha 40 hp problem

    after the motor slows down and you turn the motor off, how long do you have to wait until you can run at full power again?

  3. #3

    Default Re: 1998 Yamaha 40 hp problem

    Hello and thanks for your time coueytwo. My brother said as soon as it slows down, he shuts it off. waits maybe a few seconds and starts it up again and has full power like it would normally until it begins to slow down again.thanks for your help,
    shaughnny

  4. #4
    Join Date
    Jun 2010
    Location
    Milton, Fl
    Posts
    546

    Default Re: 1998 Yamaha 40 hp problem

    have someone pump the fuel bulb, when the motor starts slowing down, if this fixes it, the fuel pump is bad. what happens if he slows down, does the motor run right then?

  5. #5

    Default Re: 1998 Yamaha 40 hp problem

    Hello again,

    I just spoke with my brother and relayed to him what you had said. He said he has tried pumping the bulb and it has not helped. Also he clarified for me that when he is at full throttle and the engine begins to slow down, if he backs the throttle to about a quarter at this point the power kicks back in and he can accelerate back to full speed until it slows again. He also said that when the throttle is reduced and the linkage triggers the switch box or cdi that it has power again. Apparently he had his carbs checked at a marine repair shop and all is well there. He said that when the motor starts to slow down, if he just keeps the throttle at wide open that eventually it will slow down to a crawl and stall out. If there is anything else I can try or suggest to him, please let me know.thanks
    shaughnnhy

  6. #6
    Join Date
    Jul 2009
    Location
    kitchener, ontario
    Posts
    81

    Default Re: 1998 Yamaha 40 hp problem

    Check and clean all your wiring connections.After this is done,check the fuel lines for possible cracks or loose fittings.Good luck.

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