An electric fuel pump is a tool used to power a vehicle's engine system by providing fuel through the use of electronic means. The electric pump is a post-World-War-II innovation that made cars more efficient, reliable and affordable. The electric fuel pump is an alternative to a manual fuel pump system and is widely considered to be a better use of technology with regards to the function and operation of motor vehicles.
An electric fuel pump is small and thermally insulated to prevent sparking. Generally, it consists of a 12-volt electric motor attached to a pump assembly that pulls fuel in as the motor spins, and pushes it out through a different line that goes to the engine compartment. The fuel may pass through a fuel filter after it leaves the pump, or it may be filtered before the pump. The assembly runs at a constant pressure to allow for optimum fuel delivery to the engine without interruption and also to prevent air from getting into the fuel lines and causing problems.
Old-style fuel pumps were manual pumps that ran because the engine’s rotation caused a small arm to lift and pull fuel into a float bowl. After the fuel entered the float bowl, it could be sucked by vacuum into the carburetor to be delivered to the engine. This system was effective, but could cause problems.
Vapor lock, which occurred when the vehicle was stopped, then attempted to be started again, was one major issue with manual fuel pumps. Vapor lock occurred when hot, tiny bubbles were able to form in the fuel lines. The bubbles would not pass through the mechanical fuel pump and this would, in turn, cause the vehicle not to start. This became a common problem in the 1960s and early 1970s.
The electric fuel pump, a modern alternative to the manual pump, is mounted inside the vehicle’s fuel tank. Instead of a manual mechanism activated by the engine's rotation, a small electric pump is powered by the vehicle’s electrical system. This means the pump is independent of the operation of the engine.
The electric fuel pump can deliver more fuel at a higher pressure to help the engine get all of the fuel that it needs. Because the electric fuel pump pressurizes the fuel system before the engine is started, there is always a constant supply of fuel available in the lines at the proper pressure. There are also no air bubbles to cause vapor lock.