Fuel Delivery and Air Induction: Description and Operation

PURPOSE

Fuel Delivery

Fuel Delivery System:

The fuel system supplies the fuel injectors with clean fuel at a controlled pressure throughout the entire RPM range and under all operating conditions. The system is called Sequential Fuel Injection (SFI).

Air Induction
The air induction system filters, controls, silences and delivers fresh air to the engine.

OPERATION

Fuel Delivery

Fuel Delivery System Schematic:

The Fuel Pump (FP) is a Powertrain Control Module (PCM) output signal that is used to control the electric fuel pump. For electric fuel pump operation, the PCM grounds the FP circuit, which is connected to the coil of the FP relay, located within the Constant Control Relay Module (CCRM). This energizes the coil and closes the contacts of the relay, sending battery voltage through the power-to-pump circuit to the electric FP.

A high-pressure in-tank mounted fuel pump delivers fuel to the fuel injection supply manifold. The fuel injection supply manifold incorporates electrically actuated fuel injectors mounted directly above each of the engine's intake ports.

Fuel pressure across the injectors is maintained by a pressure regulator. Because fuel pressure is a constant while fuel demand is not, the system includes a fuel return line that allows excess fuel to flow through the regulator to the fuel tank.

When the ignition key is turned on, the electric fuel pump runs for about one second, but is then turned off by the PCM if a Profile Ignition Pick-up (PIP) signal is not received.

Air Induction
Air enters the system through the fresh air duct and flows through the air cleaner and is monitored by the Mass Air Flow (MAF) sensor. The metered air passes through the air duct and enters the throttle body. From the throttle body, the air passes through the intake plenum to the intake manifold, where it is mixed with fuel for combustion.