Accepted Answer

The key to keep this from happening is to disconnect the fuel line between the tank and the engine and drain the float bowl of fuel when the engine is left to set for more than a couple of weeks and keeping fresh fuel in your tank at all times.

When fuel is left in the float bowl it can evaporate away as the bowl is vented to the atmosphere, when it evaporates it leaves behind solids.(this happens quicker it the hot summer months) These solids are very sticky when they have been there for a short period of time. This can gum up jets and fuel pasages and cause the inlet needle to stick in the seat, it can stick open or closed, either not getting any fuel to the bowl or the bowl will overflow. The passage ways and jets in this carb are very small and clog with ease, but thats where the fuel efficientcy of a four stroke motor comes from, precise metering of the fuel.

A Yamaha boat mounted 10 micron water seperating fuel filter may help filter out anything coming from the fuel tank, I would recommend one be installed.

And you are correct about the additives, even with stabilizer added to the gas it is only good for about 6 weeks before it becomes stale, these additives will not bring dead gas back to life.

Expert:	Larry B.
Pos. Feedback:	100.0 %
Accepts:
Answered:	8/8/2009

Marine Mechanic

Mercury/ Mercruiser Certified/Verado/DTS Yamaha Two and Fourstroke Certified 26 years experience