Originally Posted by rudaire
Auto gas tanks are vented, in that they do allow air to come in to replace the fuel that is pumped out. But the vent is associated with the charcoal canister system that holds the vapors from the fuel and later introduces them into the intake of the engine to be burned..
Although not free-vented, in and out, to the outside air like boat systems are. I'm sure that the EPA is concerned about atmospheric venting of fuel vapors in boats, just like they were in automobiles. Problem is that in this case they have to tussel with the US Coast Guard and it looks like the Coast Guard is winning. So far.
I had that problem on a previous boat. It was non-fuel injected and the vent line was plugged. It DID stop working until I looked at the vent line and saw that it had an excessive amount of hose, and had tightly kinked. Unkinking it did the trick on that particular boat