CM2150 Electronic Control System – FAULT CODE 1911

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Overview

ISC and ISL Fuel Flow SMALL | MEDIUM | LARGE

Circuit Description

The electronic control module (ECM) monitors engine operating conditions, including the reading of rail fuel pressure, and changes the flow command to either increase (OPEN the electric fuel control valve) or decrease (CLOSE the electric fuel control valve) the fuel supply to the high-pressure pump.

Component Location

The fuel pump actuator is installed on the high-pressure fuel pump. The high-pressure relief valve is located on the fuel rail.

Refer to Procedure 100-002 (Engine Identification) in Section E for a detailed component location view.

Conditions for Running the Diagnostics

This diagnostic runs continuously when the engine is running.

Conditions for Setting the Fault Codes

The ECM has detected that the measured fuel rail pressure is above the commanded fuel rail pressure by a calibrated limit.

Action Taken When the Fault Code is Active

The ECM illuminates the amber CHECK ENGINE light immediately when the diagnostic runs and fails.

Conditions for Clearing the Fault Code

The ECM will turn off the amber CHECK ENGINE light immediately after the diagnostic runs and passes.

Shop Talk

Verify the electronic control module (ECM) calibration is correct. Check the calibration revision history found on QuickServe™ Online for applicable fixes to the calibration stored in the ECM. If necessary, calibrate the ECM. Use the following procedure in the corresponding Troubleshooting and Repair Manual for the engine being serviced. Refer to Procedure 019-032 in Section 19.

Fault Code 1911 is activated when the sensed rail fuel pressure reaches the opening pressure of the rail fuel pressure relief valve. Sensed pressure has exceeded system target range.

In normal engine operation, the ECM calibration varies the flow commanded to the fuel pump actuator to achieve the correct fuel rail pressure. System failures that cause loss of pressure control can cause the fuel rail pressure relief valve to open. The fuel rail pressure relief valve acts to protect the high-pressure components from over-pressurization. If the ECM detects that the fuel rail pressure relief valve is open without detection of a fuel pump actuator circuit error, Fault Code 1911 will become active. On certain applications, the ECM will attempt to reset automatically causing a momentary loss of power for less than 1 second.

Conditions that can cause Fault Code 1911:

• Purging air through the fuel system can cause a pressure overshoot, therefore causing Fault Code 1911 to log. A few bubbles exiting the line during the air in fuel test is expected. A foamy appearance is an indication of a leak that allows air to enter, a severe inlet restriction that causes cavitation, or a system that is not yet primed. If fuel inlet restriction is not excessive, use the following procedure in the ISC and ISL CM2150 Service Manual, Bulletin 4021569. Refer to Procedure 006-020 in Section 6.
• Use the following procedure in the ISLe CM2150 Service Manual, Bulletin 4021630. The source of air entry should be isolated to one of the following: Suction fuel lines, OEM fuel lines, suction-side fuel filter assemblies, or stand-pipe(s) in the fuel tank(s).Refer to Procedure 006-020 in Section 6.
• Sustained periods of very low pressure under load followed by pressure recovery overshoot. This can be caused by high restriction due to plugged filters (Fault Code 559).
• A tampered fuel pressure sensor that reads low, a biased pressure sensor, or a poor electrical connection.
• If an intermittent electrical circuit problem with the fuel pump actuator circuit exists, it is possible for Fault Code 1911 to become active, then inactive during normal engine operation. ECM Fault Code 2311 is designed to detect electrical circuit issues with the actuator. Therefore, it is only necessary to inspect for bad connectors or harness issues for Fault Code 1911 if no other fault codes exist. An electric fuel control actuator with excessive leakage will result in high rail fuel pressures at idle or light load.
• Other conditions include ECM wiring harness issues such as poor grounds, battery voltage spikes, electrical noise, low alternator output, and large disturbances of battery voltage, as when jump-starting the vehicle.
• The fuel rail pressure sensor should also be checked. When checking the fuel rail pressure sensor accuracy, make sure the high-pressure fuel rail is not pressurized. The fuel pump, high-pressure fuel lines, and fuel rail contain very high-pressure fuel. Do not loosen any fittings while the engine is running. Once the engine is keyed off, there could be a significant amount of time waiting on the rail to depressurize to zero. It is necessary to manually relieve the pressure from the high-pressure fuel rail by loosening the pump to rail line at the rail.

Refer to Troubleshooting Fault Code t05-1911