Fuel Delivery System

Fuel Supply System:

PURPOSE
The basic function of the fuel system is to control fuel delivery to the engine under all operating conditions.

DESCRIPTION
The fuel system is controlled by the control module located in the passenger compartment. The control module is the control center of the system. Fuel is delivered to the engine by one type of fuel injection, throttle body fuel injection (TBI), and the injector is supplied fuel by the fuel supply system.
The main control sensor is the Oxygen Sensor (O2S), which is located in the exhaust manifold. The O2S tells the control module the amount of oxygen in the exhaust gas, and the control module changes air/fuel ratio to the engine by controlling the fuel injector. A 14.7:1 air/fuel ratio is required for efficient catalytic converter operation. Because the constant measuring and adjusting of the air/fuel ratio, the fuel injection system is called a "Closed Loop" system.
Several other important engine operation parameters include: engine speed, manifold pressure, engine coolant temperature and throttle. These parameters determine the "mode" of engine operation.



FUEL SYSTEM COMPONENTS
The fuel system consists of the following components:

- Throttle Body Injection (TBI) Unit
- Fuel pump.
- Fuel pump relay circuit.
- Fuel tank
- Accelerator control.
- Fuel lines.
- Fuel filter
- Evaporative Emission (EVAP) control system

BASIC SYSTEM OPERATION
The fuel supply is stored in the fuel tank. An electric fuel pump, located in the fuel tank with the fuel level gauge sending unit, pumps fuel through an in-line filter to the TBI unit. The pump is designed to provide fuel at a pressure greater than is needed by the injectors. The pressure regulator, part of the TBI assembly, keeps fuel available to the injectors at a regulated pressure. Unused fuel is returned to the fuel tank by a separate line.