try disconnecting the fuel line from the kicker next time you run the big motor and see if the bulb goes soft, neighbor has the same problem can hardly get the bulb to pressurize but doesn't seem to effect the 9.9 as far as running, if the bulb stays hard after disconnecting your sucking air from somewhere and pulling all the gas from the 9.9, check the fitting where it attaches to the kicker and make sure it's a good snug fit, then try replaceing the bulb