Fuel starvation occurs when a device powered by an internal combustion engine, most notably a vehicle of some form, cannot make use of its available fuel because of some problem with the fuel delivery system. There are a few different causes for fuel starvation, including blockages, leaks and the intrusion of water into the fuel tank. A motorized device that cannot access its fuel supply is unable to function, because internal combustion motors that do not have fuel to burn are inoperable. This can be merely inconvenient if it happens to a device such as a lawnmower, but it can be deadly if it happens to an airplane and quite dangerous if it happens to an automobile in some situations.
There are a few different factors that can lead to fuel starvation. Unused fuel may be lost through leaks in the system that delivers fuel from the tank to the engine, resulting in an inadequate supply of fuel reaching the engine. A blockage in the fuel filter or other part of the fuel delivery system also can lead to fuel deprivation. If water mixes with fuel, it tends to collect at the bottom of the tank beneath the fuel, where it will be drawn from the tank before the fuel. An internal combustion engine cannot run on water, so this also causes fuel starvation.
The term "fuel starvation" only applies to situations in which the system responsible for delivering fuel to the engine is faulty. It does not refer to situations in which the fuel supply is actually depleted, though the consequences are generally similar. "Fuel exhaustion" is the term used to describe situations in which a vehicle or other motorized device consumes all of its fuel and is rendered inoperable because there is no more fuel to use.
Aviators must pay particular attention to the problem of fuel starvation, because the consequences of mid-flight engine failure can be quite severe. While proper planning can generally prevent fuel exhaustion, it can do little to prepare for or to prevent fuel deprivation. Regular maintenance, inspection and testing of the engines and fuel systems are the best ways to ensure the fuel is actually reaching the engine. It is not particularly common for airplane fuel delivery systems to fail to provide fuel for the engines, but it only takes one failure of such a system to seriously endanger the lives of all of those on the airplane.