The entire behavior of the fuel pump is based on simple fluid dynamics and the exchange of pressure which causes the gas to flow as well as stop when the gas reaches the top of the tank.

Gas pumps are designed to stop the flow of gas once your car’s tank has filled up. But as many drivers know, you can pull the trigger and pump a little more gas before the pump will click off again.

In your gas tank is a fuel pump, says Bill Evans, who's worked with cars for over 30 years and is now manager of J & E Auto ...