General System Description

PURPOSE
The purpose of the fuel supply system is to provide the fuel metering system with a constant supply of high pressure fuel.

OPERATION
The fuel supply is stored in the fuel tank. An electrical fuel pump contained in the modular fuel sender assembly pumps fuel through an in-line fuel filter to the fuel rail assembly. The pump is designed to provide fuel at a pressure above the regulated pressure needed by the injectors.

Fuel is recirculated through the fuel rail continuously while the engine is running. This removes air and vapors from the fuel as well as keeping the fuel cool during hot weather operations.

The fuel pressure regulator that is mounted on the fuel rail, maintains a variable pressure across the injectors based on intake manifold vacuum (load). It is accomplished by controlling the amount of fuel that is recirculated back to the fuel tank.

Unleaded fuel must be used with all gasoline engines for proper emission control system operation. Using unleaded fuel will also decrease spark fouling and extend engine oil life. Leaded fuel can damage the emission control system, and its use can result in loss of emission warranty coverage.

All vehicles with gasoline engines are equipped with an Evaporative Emission System that minimizes the escape of fuel vapors to the atmosphere.

FUEL PUMP ELECTRICAL CIRCUIT
When the key is first turned ON the PCM energizes the fuel pump relay for two seconds to build up the fuel pressure quickly. If the engine is not started within two seconds, the PCM shuts the fuel pump OFF and waits until the engine is cranked. When the engine is cranked and the RPM signal has been detected by the PCM, the PCM supplies 12 volts to the fuel pump relay to energize the electric in-tank fuel pump.
An inoperative fuel pump relay can result in a no start condition.
An inoperative fuel pump would cause a no start condition. A fuel pump which does not provide enough pressure can result in poor performance.