mysteries of outboard motor behavior - SailNet Community

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Old 06-21-2007
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mysteries of outboard motor behavior

Here's a newbie question for y'all:
I have a 9.9 hp Yamaha outboard on my boat. I recently replaced the fuel line with squeeze bulb to resolve a no-start problem. Now it starts every time with the push of a button! Then it runs for 10-20 minutes with no problems, then it dies. At which point I open the locker and squeeze the bulb a few times and then it starts right up again and runs for 10-20 minutes and then dies. Repeat...
So, why does it do this?
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Old 06-21-2007
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Mmmm...Did you open the vent screw on the fuel tank? (Don't ask me why I know this.)

Any pinholes or cracks in the fuel line or conenctions, that are letting air get into the line and breaking the suction to the fuel?
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Second the idea of the vent, or possible air leaks...
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Check the filter(screen) on the inside of the tank.
Sounds like it might be plugged up.
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If you have opened the vent, then my guess it is the carburetor or the fuel filter. Another possibility is that you have an air leak in the fuel like... a common place for this to happen is the banjo bolts in the fuel line.
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Old 06-23-2007
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Thumbs up thanks

Thanks, everyone. This forum is a great resource. Yes, the vent cap is open while motor is running. I will check for possible air leaks, clean the intake screen, and replace the fuel filter.
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Old 06-23-2007
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Although with it restarting so quickly it does not seem likely that it could be overheating, but is the waterpump working?
Also when you squeeze the bulb is it hard?
AL
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It may also be a bad fuel pump, but I would bet on a bad quick-connection first.
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Did you do any maintenance on the engine prior to this recent bout of usage? If so, did you touch the fuel lines in anyway.... if so, likely you overtightened a banjo bolt and mangled the copper washer, and it will leak air.
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You know what the first rule of sailing is? ...Love. You can learn all the math in the 'verse, but you take
a boat to the sea you don't love, she'll shake you off just as sure as the turning of the worlds. Love keeps
her going when she oughta fall down, tells you she's hurting 'fore she keens. Makes her a home.

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