Fuel has to be pumped from the fuel tank to the engine and delivered under low pressure to the carburetor or under high pressure to the fuel injection system
Fuel pumps contain a flexible diaphram that encloses a variable volume chamber of fuel on one side
Another benefit of a tank mounted fuel pump is that a suction pump at the engine could suck in air through faulty hose connections, while a leaking connection in a pressure line will show itself immediately
A potential hazard of a tank mounted fuel pump is that all of the fuel lines are under high pressure, from the tank to the engine. Any leak will be easily detected, but is also hazardous
The electric fuel pump is generally on whenever the car's ignition switch is in the on position
The metering of the fuel into the engine is performed by the fuel-injection or carburetor systems
