Circuit DescriptionThe ECM monitors engine operating conditions, including the reading of rail fuel pressure, and changes the flow command to either increase (open the fuel pump actuator) or decrease (close the fuel pump actuator) the fuel supply to the high-pressure pump.

Component LocationThe fuel pump actuator is located on the engine-mounted fuel pump.

Conditions for Running the DiagnosticsThis diagnostic runs continuously when the engine is operating.

Conditions for Setting the Fault CodesThe ECM has detected that the fuel rail pressure reading has exceeded the commanded fuel rail pressure.

Action Taken When the Fault Code is ActiveThe ECM illuminates the amber CHECK ENGINE lamp and/or the malfunction indicator lamp (MIL) immediately when the diagnostic runs and fails.Conditions for Clearing the Fault CodeTo validate the repair using a Diagnostic Road Test, utilize a route that incorporates both stop-and-go city driving and steady state highway driving. It may be necessary to load the unit for certain diagnostics in the ECM to run.To validate the repair using a Chassis Dynamometer Test, utilize a routine that incorporates acceleration and motoring events, steady state highway operation, and load. This will simulate normal driving and allow the diagnostics in the ECM to run.The fault code status displayed by INSITE? electronic service tool will change to INACTIVE immediately after after the sensed fuel rail pressure meets commanded pressure and the diagnostic runs and passes.The ECM will turn off the amber CHECK ENGINE lamp after the diagnostic runs and passes.For On-Board Diagnostic (OBD) engines, the ECM will turn off the MIL after three consecutive trips where the diagnostic runs and passes.The ?Reset All Faults? command in INSITE? electronic service tool can be used to clear active and inactive faults, as well as extinquish the MIL for OBD applications

Shop TalkA fuel pump actuator with excessive leakage or a damaged inboard o-ring will result in high fuel rail pressures at idle or light load.

If the fuel pump actuator exhibits excessive leakage, it is possible that the fuel rail pressure will reach the opening pressure of the fuel rail pressure relief valve and Fault Code 1911 can possibly also become active.

Possible Cause:1) Fuel rail pressure sensor failure2) High fuel drain line failure3) Fuel pump Actuator failure4) ECM calibration