Fuel Delivery System

Fuel Supply System:

FUEL SYSTEM OVERVIEW
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 fuel system is controlled by the control module located in the engine compartment. The control module is the control center of the system. The basic function of the fuel system is to control fuel delivery to the engine under all operating conditions.

The main control sensor is the Heated Oxygen Sensor (HO2S). The HO2S is located in the exhaust manifold. The HO2S tells the control module the amount of oxygen in the exhaust gas. The control module changes the air to fuel ratio to the engine by controlling the fuel injector. Efficient catalytic converter operation requires a 14.7:1 air to fuel ratio. Because the constant measuring and adjusting of the air to fuel ratio, the fuel injection system is called a Closed Loop system.

Several other important engine operation parameters include the following items:

- The engine speed.
- The manifold pressure.
- The engine coolant temperature.
- The throttle position.

These parameters determine the mode of engine operation. Refer to Modes of Operation. Modes of Operation

FUEL METERING SYSTEM COMPONENTS
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 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.


FUEL SUPPLY COMPONENTS
The fuel supply is stored in the fuel tank. An electric fuel pump, located in the fuel tank with the gauge sending unit, pumps fuel through an in-line fuel filter to the fuel meter body assembly.

The pump provides fuel at a pressure greater than is needed by the injectors. The fuel pressure regulator, part of the fuel meter body assembly, keeps the fuel to the injectors at a regulated pressure. Unused fuel is returned to the fuel tank via a separate line.