Yahama 9.9 fuel issues

DollarBoat

Seaman Apprentice
Joined
Mar 6, 2016
Messages
33
I have a Yamaha 9.9 (t9.9exhw) which is plumbed to my main tank. When running it, the ball to pump the gas goes flat and the motor dies. If I keep pumping the ball it runs fine and if I stop, it deflates. I noticed when I took the cover off the motor, gas was dripping out from the bottom of the carb. Could this be the problem?
 

99yam40

Fleet Admiral
Joined
Sep 7, 2008
Messages
8,851
they are not suppose to leak fuel, solve that 1st then look for a restriction if primer bulb is being sucked flat
 

DollarBoat

Seaman Apprentice
Joined
Mar 6, 2016
Messages
33
Thanks. I wasn't sure if that was an overflow thing since I only noticed it when the motor was off. I'll see about getting a kit to rebuild it.
 

MistaTubbs

Cadet
Joined
May 25, 2016
Messages
6
Check the fuel pump too..Compared to carbs it's a piece of cake.

Also, it's worth noting that my primer bulb doesn't always remain taught either. I do, however, run the engine with the gas tank with the screw cap 75ish% open and it seems to do fine.
 

pro-crastinator

Chief Petty Officer
Joined
Dec 12, 2013
Messages
453
How long has the motor been plumbed to the onboard tank?
Do you always have the fuel cap uscrewed 75%
Is the onboard tank vented? (old type) Or is one of the newer epa non vented varieties.?
Unvented tank + run motor = flat pumper bulb. ----------- is one "formula" that comes to mind.

Am unsure what "taught" means. primer bulb is either "inflated" (normal) so that you can pump it, OR flat (as a pancake) which prevents you from actually using it to move fuel to the carb.
 
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