Steve, once the tank is filled and vapors have dissipated I would not expect that you'd get much in the way of fumes from your tank vent. The only time it might push some fume laden air out is if the ambient temperature rises significantly, or the barometric pressure drops, and even then it won't be much. The bulk of my gasoline smell was from a leaky fuel pressure regulator, and another good source is flexible hose that's not 100% sealed for fuel and might wick just a tiny amount through the pores of the liner.