THE BEECHMONT CREST AUTOMOTIVE LEARNING ZONE
FUEL PUMP
A fuel pump uses pressure to draw fuel out of the tank and route it to the engine. There are two basic types of fuel pump: mechanical and electric. Electric pumps are used on all recent model vehicles. Mechanical pumps still exist on vehicles that use carburetor fuel systems.
A mechanical fuel pump is bolted to the side of the engine block. The pump is powered by an egg-shaped lobe on the camshaft. During the intake stroke, a vacuum is created within the pump. This vacuum draws fuel into the pump. On the outtake stroke, pressure pushes the fuel out.
An electric fuel pump is usually located in or near the fuel tank-- often in the fuel line between the tank and the engine. In many modern vehicles, the designs of the tank and the fuel pump are closely integrated.
Whereas pressure builds gradually within a mechanical fuel pump, an electric fuel pump creates pressure almost instantly. Electric fuel pumps also minimize a problem common in mechanical pumps: vapor lock. Vapor lock occurs when bubbles in overheated fuel reduce flow to the engine. Since electric pumps are located farther away from the engine’s intense heat, they are much less prone to vapor lock.