Chart A-8 Fuel System Diagnosis

Fig. 006 - Wiring Diagram for Chart A-7 Fuel System Diagnosis. VIN 3, VIN 9:

Fig. 009 - Chart A-8 Fuel System Diagnosis.:

CHART DESCRIPTION
Number(s) below refer to circled number(s) on the diagnostic chart.

1. Pressure but, less than 234kPa (34 psi) falls into two areas:
a. Regulated pressure but less than 234 kPa (34 psi). Amount of fuel to injectors OK but pressure is too low. System will be lean running and may set Code 44. Also, hard starting cold and overall poor performance.
b. 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.

2. Restricting the 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).
3. This test determines if the high fuel pressure is due to a restricted fuel return line or a pressure regulator problem.