Fuel Delivery and Air Induction: Description and Operation

Fuel Metering System:

PURPOSE
The function of the fuel metering system is to deliver the correct amount of fuel to the engine under all operating conditions.

OPERATION
Fuel is delivered to the engine by individual fuel injectors mounted in the intake manifold near each cylinder. The main control sensor is the Oxygen (02) sensor, which is located in the exhaust manifold. This sensor tells the Electronic Control Module (ECM) how much oxygen is in the exhaust gas, and the ECM changes the air/fuel ratio to the engine by controlling the fuel injectors.
The best mixture to minimize exhaust emissions is 14.7:1, which allows the 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.

COMPONENTS
The fuel metering system consists of the following parts:

^ Fuel tank
^ Fuel pump
^ Fuel lines
^ Fuel pump electrical circuit,
^ Fuel injector rail
^ Fuel injectors
^ Pressure regulator

Throttle body assembly, including:

^ Idle Air Control (IAC) valve
^ Throttle Position Sensor (TPS)