Chart A7 (2 Of 2) - Fuel System Diagnosis

NOTE: Test numbers refer to test numbers on diagnostic chart.

1. Has regulated fuel pressure, but pressure is less than 9 psi (.6 kg/cm² ). Check the following when this condition occurs:
   • Amount of fuel to injectors is okay, but pressure is too low. Fuel system will be running lean and may set Code 44. Also exhibits hard starting cold and poor overall performance.
   • Has restricted fuel flow causing pressure drop. Normally, a vehicle with a fuel pressure of less than 9 psi (6.2 kg/cm² ) 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 fuel return line allows the fuel pump to develop its maximum pressure (dead head pressure). When battery voltage is applied to the fuel pump test terminal, pressure should be 13-18 psi (90-124 kg/cm² ).
3. This test determines if the high fuel pressure is due to a restricted fuel return line or throttle body pressure regulator malfunction.

Fig 1: Chart A7 - System Schematic, Fuel System Diagnosis

Fig 2: Chart A7 - Fuel System Schematic

Fig 3: Flow Chart A7 (2 of 2) Fuel System Diagnosis

Fig 4: Flow Chart A7 (2 of 2) Fuel System Diagnosis