Fuel Delivery and Air Induction: Description and Operation

FUEL METERING
The Engine Control Module (ECM) is in complete control of this fuel delivery system during normal driving conditions.
The intake manifold function, like that of a diesel, is used only to let air into the engine. The fuel is injected by separate injectors that are mounted over the intake manifold.
The air drawn into the engine is sensed by the air flow sensor.
This sensor generates the voltage according to the flow of the air drawn into the engine.
The changing voltage is transformed into an electric signal and provided to the ECM.
After receiving signals sent from the air flow sensor, and others, the ECM determines an appropriate fuel injection pulse width, referring to the programmed data, and sends this information to the fuel injector valves to effect an appropriate air fuel ratio.
In the Port Fuel Injection system, the injectors turn on at every crankshaft revolution. The ECM controls the injector on time so that the correct amount of fuel is metered depending on driving conditions.
Two interchangeable "0" rings are used on the injector that must be inspected when the injectors are removed. Check "0" rings for cuts or other damage and replace as necessary.
The fuel rail is attached to the top of the intake manifold and supplies fuel to all the injectors.
Fuel is recirculated through the rail continually while the engine is running. This removes air and vapors from the fuel as well as keeping the fuel cool during hot weather operation.
The fuel pressure regulator, mounted on the common chamber, maintains a pressure differential across the injectors under all operating conditions. It controls the amount of fuel that is recirculated back to the fuel tank, based on engine demand.