Sometimes it is tempting to see how many miles you can get out of your tank of gas, but you should not do it! The video shows the innards of a fuel pump and it will help you understand why.
Your car's fuel pump sends gasoline from the tank to the engine, which is a crucial component in getting your car running, but it has a tendency to fail and leave you stuck on the side of the highway, especially if you like to run your car low on gas.
The key bits of a fuel pump that tend to cause problems when you run your car low on gas are the strainer, fuel filter and electric motor. As you can see in the video above, the electric motor is actually cooled by the fuel. Gasoline from the tank enters in through the strainer (or “filter sock” as he calls it in the video), gets squeezed via a round impeller style pump (shown below), and is pushed through the electric pump motor to cool the copper windings that make the motor work.
Running a vehicle out of fuel means air, not liquid gasoline, has to do the job of cooling the windings. Since flowing gases tend to have lower convective heat transfer coefficients than liquids, they aren’t able to remove heat from the windings as effectively, meaning the fuel pump electric motor can overheat, melt its windings and ultimately croak.
So don't run your car low on fuel, you do not want to get stuck on the side of the highway on your way to the office. Keep an eye on that gauge - which gets its reading from that float-based voltage divider setup shown in the video - and try to keep the "running on fumes" to a minimum.