alpha one idle problem

Discussion in 'Sterndrives' started by dwcrabs, Jan 27, 2009.

  1. dwcrabs
    Joined: Jan 2008
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    Location: maryland

    dwcrabs New Member

    I have a 3 year old merc alpha one. last year i started to have a problem. the engine will fire up and run at idle speed when the motor get warm it starts to sputter and cuts off. when i am finally able to get it out of the dock it runs great at speed and on plane. but when i cut the speed down to go into a dock of put the gear in nuetral it cuts off again. do i need to adjust the idle or is there some other problem any suggestion would be appreciated.
  2. CDK
    Joined: Aug 2007
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    Location: Adriatic sea

    CDK retired engineer

    Your problem is in the carb, where some sediment has restricted the idle jet. When cold, the choke valve is closed so there is more vacuum to obtain enough fuel and at speed the main jets supply whatever is needed.
    But at warm idle all depends on the idle jet and the small bore which connects it to the float chamber.
    Remove the carb, take it apart and clean it. You will find some sludge on the bottom of the float chamber and in the passages. I've often wondered how it gets there after passing two fuel filters.
    Take care when you take off the carb's top cover: the gasket there is easily damaged.
  3. tuantom
    Joined: Jan 2005
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    Location: Chicago

    tuantom Senior Member

    I wouldn't turn the idle up to compensate - I think alpha 1's like to shift at low rpms. I've heard they commonly have a neutral safety switch (or a temporary kill switch to lower rpms during shifting) problems - though like CDK said, your issues sound carb related.
  4. designer4life
    Joined: Dec 2008
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    Location: Erie Pa

    designer4life Junior Member

    A buddy of mine had the same exact problem and i can re-asure you that it is carb related. My buddy went the full 9 yards and got a whole rebuild and it seemed to fix the problem.

  5. PAR
    Joined: Nov 2003
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    Location: Eustis, FL

    PAR Yacht Designer/Builder

    A rebuild kit for those carbs is quite inexpensive and should be used, rather then re-using old gaskets. Toss the new parts into the well cleaned carb, set the float and reassemble. Varnish accumulates in the passageways if fuel is left to evaporate, instead of drained. Over time, this will restrict orifices and parts movement and must be cleaned out.

    Next time you plan to leave the boat for an extended amount of time (without starting) use a fuel stabilizer and also drain the fuel system.
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