Fuel Metering System

Fuel Meter Body Assembly:

FUNCTION
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 and poppet nozzles mounted in the intake manifold near each cylinder.

The main control sensor is the Heated Oxygen Sensor (HO2S) located in the exhaust manifold. This sensor tells the Control Module how much oxygen is in the exhaust gas, and the Control Module changes the air and fuel ratio to the engine by controlling the injectors. The best mixture to minimize exhaust emissions is 14.6:1 which allows the catalytic converter to operate most efficiently. Because of the constant measuring and adjusting of the air and fuel ratio, the fuel injection system is called a Closed Loop system.

The fuel metering system consists of the following parts:

- The fuel supply components (fuel tank, pump, lines)
- The fuel pump electrical circuit
- The fuel meter body assembly which includes the following components:

- The SFI fuel injectors and poppet nozzles
- The fuel pressure regulator
- The electrical wiring harness

- The upper manifold assembly which includes the following items:

- The throttle body
- The Idle Air Control (IAC) valve
- The Throttle Position (TP) sensor
- The Manifold Absolute Pressure (MAP) sensor