I have a 1989 48 HP Evinrude. I am having trouble keeping the bulb tight so the engine is not starting. I have to choke it to get it started and then it dies while idling. I recently had a carberator kit installed. I also have a new fuel line from the gas can to the motor. The bulb will tighten up for about 5 to 7 seconds when pumped and then will go soft. I can't see gas coming out anywhere in the motor to indicate a leak. Any suggestions on where I should look nextto solve the issue?