General Operation

Fuel Metering:

PURPOSE
The function of the fuel metering system is to deliver the correct amount of fuel to the engine under all operating conditions. Fuel is delivered to the engine by individual fuel injectors mounted in the intake manifold near each cylinder.

Fuel Injection System:

OPERATION

Fuel Injection
The Engine Control Module (ECM) controls fuel delivery system during normal driving conditions. Intake manifold is used only to let air into engine. Fuel is injected by separate injectors, into all cylinder inlet ports at the same time once every engine revolution. Using this method two injections of fuel are required to produce the charge for each combustion cycle.

Fuel/Vapor System:

Fuel Delivery
Fuel is pumped by an electric pump mounted inside fuel tank, through a fuel filter, to fuel rail.

Fuel rail is attached to top of intake manifold and supplies fuel to all injectors. Fuel is recirculated through rail continually while engine is running. This removes air and vapors from fuel as well as keeping it cool.

Fuel Pressure
Fuel pressure regulator is mounted on fuel rail and maintains a pressure differential across injectors under all operating conditions.
The main control sensor is the heated oxygen sensor, which is located in the front pipe. The heated oxygen sensor indicates to the engine control module the amount of oxygen in the exhaust gas, and the engine control module changes the air/fuel ratio to the engine by controlling the fuel injectors. The best air/fuel ratio to minimize exhaust emissions is 14.7 to 1, which allows the three way catalytic converter to operate most efficiently. Because of the constant measuring and adjusting of the air/fuel ratio, the fuel injection system is called a "Closed Loop" system.