Fuel Delivery and Air Induction: Description and Operation

GENERAL DESCRIPTION
The fuel delivery components consist of fuel supply lines, a high pressure fuel pump (mounted in the fuel tank), a fuel filter assembly, and a fuel pressure regulator. The delivery system's function is to deliver fuel at a pressure and quantity high enough to allow the fuel regulator to maintain a constant fuel pressure in the fuel delivery rail (in reference to the intake manifold pressure) under all driving conditions. Additionally a check valve in the fuel pump holds pressure against the system for a period of time after engine shutdown to ensure adequate pressure is available during warm engine re-start conditions.

FUEL INJECTORS
The injectors are solenoid operated shutoff valves designed to deliver fuel in an appropriate spray pattern to promote total fuel atomization in the intake air stream

FUEL CONTROL SYSTEM
The fuel injection control system consists of the Engine Control Module (ECM) and all of the engine and operating condition sensors. Using the information from the sensors to determine the proper fuel amount and delivery time, the ECM varies the injectors "ON" time to adjust the amount of fuel delivered during each individual firing cycle.

For a more detailed description of the fuel injection system operation, refer to COMPUTERS AND CONTROL SYSTEMS. For all Fuel System mechanical component descriptions, refer to this section by component name.

FUEL DELIVERY AND RETURN
The fuel return portion of the fuel system consist of lines and couplings working with the fuel supply lines. The function of the return line is to recover excess fuel vented by the fuel pressure regulator (mounted on the fuel rail) and return it to the fuel tank. The fuel return line is low pressure and returns directly to the fuel tank.

The vapor recovery system also consists of lines and couplings. The function of the vapor lines are to provide a route for the recovery of fuel vapors (from the fuel tank) either for storage in the charcoal canister, or for evacuation through the purge control system. Additionally contained in the vapor recovery system are two components, an overfill limiter and a fuel check valve. These components primary functions are as evaporative emissions control devices and are therefore covered in detail in EMISSION CONTROL DEVICES.