While running your car on fumes might seem like a tempting idea to eke out as many rounds from your tank as possible, but the results can be utterly catastrophic.
The video below elaborates the workings of a fuel pump, and it should be an enough deterrent for you to never let your fuel gauge hit “Empty” again. As the YouTuber speedcar99 explains, the fuel pump is used to send gas from the tank to the engine cylinders and is a crucial part of keeping your car up and running. Key parts include the strainer, fuel filter, and electric motor. But it can fail, with terrible results for your car and your pocket, if you insist on running the car when it’s low on fuel.
The electric motor, as elaborated in the video, is cooled by the fuel. Fuel enters via the strainer, is compressed by a round impeller style pump and is then pushed ahead by an electric pump motor to cool the copper windings on the motor.
Running on low fuel means spraying air, not fuel, on the windings. Air can also cool down the motor, but since gases have a lower convective heat transfer coefficient than liquids, they are nowhere near as efficient in heat removal as the fuel, meaning after some time the fuel pump motor will overheat and eventually burn.
Fuel is also used as a lubricant for the pump, so if you have a habit of running your car on low fuel, it can cause premature wear of rotating parts.
In short, it’s best to keep your tank at least half full at all times, both for the sake of your convenience and your car’s health.