Gasoline Fuel System

The fuel rail pressure (FRP) sensor (Figure 37) senses the pressure difference between the fuel rail and the intake manifold. The return fuel line to the fuel tank has been deleted in this type of fuel system. The differential fuel/intake manifold pressure together with measured fuel temperature provides an indication of the fuel vapors in the fuel rail. Both differential pressure and temperature feedback signals are used to control the speed of the fuel pump. The speed of the fuel pump sustains fuel rail pressure which preserve fuel in its liquid state. The dynamic range of the fuel injectors increase because of the higher rail pressure, which allows the injector pulse width to decrease.

Fuel System - 4.6L, 5.4L and 6.8L

Component Location - Gasoline











WARNING: Fuel in the fuel system remains under high pressure even when the engine is not running. Before repairing or disconnecting any of the fuel lines or fuel system components, the fuel system pressure must be relieved to prevent accidental spraying of fuel, causing personal injury or a fire hazard.

The vehicle:

^ is equipped with a multiport fuel injection (MFI) system.
^ has separately controlled fuel injectors mounted to the intake manifold for each cylinder.
^ has fuel injectors which are supplied with pressurized fuel from the fuel pump through the fuel injection supply manifold.
^ has a fuel injection supply manifold which is equipped with a fuel rail pressure (FRP) sensor.