Fuel Delivery and Air Induction: Description and Operation

Model R620 Fuel Rail Assembly:

Fuel Metering Components:

PURPOSE
To attain 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.

GENERAL SYSTEM DESCRIPTION:
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 Engine 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.

COMPONENTS
The fuel metering system consists of the following parts:
Fuel injector rail assembly, including:
- Fuel injectors
- Pressure regulator
Throttle body assembly, including:
- Idle Air Control (IAC) valve
- Throttle Position Sensor (TPS)

FUEL SUPPLY SYSTEM DESCRIPTION:
The fuel supply is stored in the fuel tank. An electric fuel pump, located in the fuel tank with the gage sending unit, pumps fuel through an in-line fuel filter to the fuel rail assembly. The pump provides fuel at a pressure greater than is needed by the injectors. The pressure regulator, part of the fuel rail assembly, keeps fuel available to the injectors at a regulated pressure. Unused fuel is returned to the fuel tank by a separate line.

PURPOSE
To provide the metering system with a constant supply of high pressure fuel.

COMPONENTS
- Fuel tank
- Fuel pump
- Fuel lines
- Fuel pump electrical circuit,