The electric fuel pump is the heart of every electronic fuel injection system. Let's review the basics of this critical fuel injection part.

Usually located inside or near the fuel tank, the fuel pump's job is twofold:

1) To push fuel from the tank to the injectors, and

2) To create sufficient pressure so the injectors will deliver the correct amount of fuel under all operating conditions.

The pressure developed by the pump, as well as the volume of fuel it flows, must both meet the vehicle manufacturers' requirements or engine performance, economy and emissions will suffer.

The amount of fuel pressure required for a given application will vary depending on the type of injection system (L-Jetronic, CIS, Motronic, etc.), the flow characteristics of the injectors and the engine's fuel requirements.

For example, certain Audi models with Bosch Motronic require 55 to 61 psi (3.8 to 4.2 BAR) of static pressure measured with the engine off. By comparison, a BMW may require 43 psi (3.0 BAR) on some models or 48 psi (3.3 BAR) on others. The differences may not seem like much, but a few pounds of fuel pressure can have a significant impact on engine performance and emissions.