That tube is the vent side of the fuel pump diaphram. On a car it would
just be a hole in the fuel pump. When the diaphram in th epump leaks fuel
would leak out the hole. On a baot because it has a tube in it and it goes
to the carb it can't fill your bilge with gas.

"Kevin Jed" wrote in message
m...
I have a Mercruiser 120 fuel problem. There is a small tube going from the
fuel pump to the throat of the carburetor (like a vacuum tube) and it is
injecting a large volume of fuel into the carburetor throat, bypassing the
float assembly altogether and flooding the engine. When I remove this tube
and attempt to plug it, the engine runs properly but there is so much
pressure on this little tube it blows the plug out and starts pouring raw
fuel into the boat! Automotive engines don't have this tube, and I don't
know what it's purpose is. Can anyone offer any help? Thanks!