When you start to pump gas, the pipe, which has been “blocked” like the hose ... filling your tank. And once it’s full, gasoline, not air, now reaches the pipe inside the nozzle, which ...

On certain sport utility vehicles, there is a breather hose that attaches to the nozzle of the on-board refueling vapor recovery (ORVR) valve, which is located on the topside of the fuel tank.