Ive always been taught it was bad on your fuel pump to run your vehicle tank close to dry as it would damage the fuel pump but Ive never seen any validation to support this statement. So will running a tank dry before fill up damage your fuel pump?
Yes, running low on fuel can damage your fuel pump, but as IHaveNoIdeaWhatImDoing mentioned in the comments below, modern fuel tanks are sophisticated enough to prevent fuel pump starvation until the tank is almost complete empty.
Either way, damage to the pump can occur because fuel acts as a coolant for the electric motor. When there is no more fuel the pump will suck up air, causing it to overheat, thus increasing the potential for damage.
It is because the fuel lubricates and cools the pump.
If you leave the tank run dry, the fuel pump will turn dry, which will overheat it and may cause the electric motor to fail or otherwise to reduce its service life.
The same principle applies to the water pump when it is electrically driven, like in the Toyota Prius. When burping those kind of systems, care should be taken of not allowing the water pump also to turn dry for too long.