Car manufacturers don’t mention this, but it is important not to drive “on fumes”. As a matter of fact, AC Delco in its Women’s Car Care Seminar recommends that we make a stop at the gas station any time the tank is less than 1/3 full.
The reason for this advice is to protect the fuel pump. The fuel pump in modern vehicles is an electrical/mechanical device. All such devices need to be cooled. There are two ways that a fuel pump is cooled:
1) Gasoline flows through it and heat passes from it to the engine.
2) The fuel pump is immersed in gasoline and cooled in a fuel bath.
As the fuel tank gets close to empty, this second way of cooling the fuel pump becomes less and less effective.
Running “on fumes” will usually not destroy your fuel pump immediately but it does cause it to work at higher than optimal temperatures. Over time, this will cause faster wear. That may make it necessary to replace the fuel pump sooner than expected.
Another reason not to run “on empty” is that fuel pumped from a “dry” tank may contain moisture and deposits. Over time, these contaminates could damage the fuel filter or the fuel pump itself.
So be good to your fuel pump – keep the fuel tank at least 1/3 full at all times.
This will also keep you from running out of gasoline. Being out of gas is not only a hassle, but… you guessed it – it’s really bad for the fuel pump.