As has been stated, the vent is keep fuel out of the crankcase if/when the diaphragm ruptures and it goes to the outer bowl vent of your carburetor. Only marine versions of both carbs and pumps have these vents, so you might have the wrong carb. My Mercruiser was converted to an electric pump and the previous owner just left the tube dangling from the carburetor. It was strategically placed over the starter and he was perplexed why he went through starters.
Its capped off now. Fuel and fuel vapors are dangerous. Please use extreme care when working with these systems.As has been stated, the vent is keep fuel out of the crankcase if/when the diaphragm ruptures and it goes to the outer bowl vent of your carburetor. Only marine versions of both carbs and pumps have these vents, so you might have the wrong carb. My Mercruiser was converted to an electric pump and the previous owner just left the tube dangling from the carburetor. It was strategically placed over the starter and he was perplexed why he went through starters.
I am not sure what would happen, but it might possibly dump raw fuel overboard which is not acceptable. As expensive as they are, if it were my boat, I would find a carburetor appropriate for the application or at a minimum, switch to an electric pump.
