Part 2 of 2

Chart A-7 Part 2 Of 2:

Fuel System Diagram:

CIRCUIT DESCRIPTION:

The fuel pump will deliver fuel to the fuel rail and injectors, then to the pressure regulator, where the system pressure is controlled. Excess fuel pressure is bypassed back to the fuel tank. When the engine is stopped, the pump can be turned "ON" by applying battery voltage to the test terminal located in the engine compartment.

Improper fuel system pressure may contribute to:

^ Codes 44 or 45.
^ "Cranks But Won't Run" condition.
^ Hesitation, loss of power, poor fuel economy.
^ Cuts out, feels like an ignition problem.

NOTE: Because of all the possible color code combinations used on electrical wiring diagrams, always refer to SCHEMATIC DIAGRAMS/ELECTRICAL AND ELECTRONIC WIRING DIAGRAMS/ECM CONNECTOR IDENTIFICATION for correct color code identification of circuit.

TEST DESCRIPTION Numbers below refer to circled numbers on the diagnostic chart.

5. Pressure less than specifications falls into two areas:

^ Regulated pressure but less than specifications; the amount of fuel to injectors is OK, but pressure is too low, The system will be lean running and may set Code 44. Also, possible hard starting cold and overall poor performance.

^ Restricted flow causing pressure drop; Normally, a vehicle with a fuel pressure of less than 165 kPa (24 psi) at idle will not be driveable. However, if the pressure drop occurs only while driving, the engine will normally surge then stop as pressure begins to drop rapidly.

6. Restricting the fuel return line allows the fuel pump to develop its maximum pressure (dead head pressure). When battery voltage is applied to the pump test terminal, pressure should be above 517 kPa (75 psi).

7. This test determines if the high fuel pressure is due to a restricted fuel return line or a pressure regulator problem.