Fuel Metering System Basic Operation

Fuel Metering System Operation

The fuel metering system is made up of the following parts:
- Fuel supply components (fuel tank, pump, and lines).
- Fuel pump electrical circuit.

- Fuel rail assembly, including:
- Fuel injectors.
- Fuel pressure regulator.

- Throttle body assembly, including:
- Idle Air Control (IAC) valve.
- Throttle Position (TP) sensor.

Basic System Operation
The fuel metering system starts with the fuel in the fuel tank. An electric fuel pump, located in the fuel tank, pumps fuel to the fuel rail through an in-line fuel filter. The pump is designed to provide fuel at a pressure above the pressure needed by the injectors. A fuel pressure regulator in the fuel rail keeps fuel available to the fuel injectors at a constant pressure. A return line delivers unused fuel back to the fuel tank. Refer for further information on the fuel tank, line filter, and fuel pipes.