Originally posted by musicman
Mike, the sound would be about the same I guess.

But, what brought my attention to this one day was coming out to the parking lot where I had parked 15 minutes earlier and finding gas dripping under the truck. It was coming from the sending unit gasket. Since then I have limited myself to half tank fill ups and relieving the pressure continuosly. When I unscrew the cap in feels like air coming out not going in.
all i know is on the tank side of the fuel pump the pump is sucking and on the carb. side the pump is pumping. in my mind if the pump is sucking and there is no vent then you are pulling a vac. on the tank. just something i have always belived, i guess i could be wrong. but i dont think so. its causing some heat build up and the gas is expanding.

i guess its like a wind noise in a car. if you have a wind noise around you door glass, going down the rd. is that air coming into the car or air being pulled out of the car?