Chart A7 - Fuel Injection

1. Pressure below 9 psi may have 2 causes:
   • Regulated pressure less than 9 psi is when fuel volume to injector is adequate but pressure is too low. System will be lean running and may set Code 44. Engine will be hard starting cold and have poor performance.
   • A restricted fuel flow is causing pressure drop. Normally, a vehicle with fuel pressure of less than 9 psi at idle will not be driveable. If the pressure drop occurs only when driving, the engine will surge then stop as pressure begins to drop rapidly.
     NOTE: The following step numbers refer to the numbers in the accompanying flow chart(s).
2. Restricting the fuel return line allows the fuel pump to develop its maximum pressure. When battery voltage is applied to the pump test terminal, pressure should be from 13 to 18 psi.
3. This test determines if the high fuel pressure is due to a restricted fuel return line or a throttle body pressure regulator problem.

Fig 1: Chart A7, Fuel Injection Flow Chart (All)

Fig 2: Chart A7, Fuel Injection Circuit Diag.

Fig 3: Chart A7, Fuel Injection Circuit Diag.