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Old 01-27-2009, 08:04 AM
dwcrabs dwcrabs is offline
Join Date: Jan 2008
Rep: 10 Posts: 2
Location: maryland
alpha one idle problem

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.
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Old 01-28-2009, 03:51 AM
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CDK CDK is offline
retired engineer
Join Date: Aug 2007
Rep: 1819 Posts: 3,277
Location: Adriatic sea
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.
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Old 01-28-2009, 07:03 AM
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tuantom tuantom is offline
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Join Date: Jan 2005
Rep: 45 Posts: 182
Location: Chicago
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.
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Old 01-28-2009, 06:47 PM
designer4life designer4life is offline
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Join Date: Dec 2008
Rep: 10 Posts: 6
Location: Erie Pa
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.
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Old 01-28-2009, 09:43 PM
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PAR PAR is offline
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Join Date: Nov 2003
Rep: 3967 Posts: 17,895
Location: Eustis, FL
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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