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 Mercedes 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 p