SPN 1387 - FMI 3 (Fault Code 2249)

SPN1387 FMI3
Injector Metering Rail 1 Pressure - Data Valid But Below Normal Operational Range - Moderately Severe Level

Fuel Rail Pressure Sensor
Fault Code: 2249
PID(P), SID(S): P157
SPN: 1387
FMI: 3/3
Lamp: Amber

REASON: Injector Metering Rail 1 Pressure - Data Valid But Below Normal Operational Range - Moderately Severe Level. The ECM has detected that the fuel pressure is lower than commanded pressure.

EFFECT: Possibly hard to start or low power. Engine could possibly not start.

Circuit Description:
The pressure control loop relies on fuel pressure supplied to the high-pressure pump by the fuel pump gear pump. The engine control module (ECM) monitors the rail fuel pressure and engine operating conditions, and changes the flow command to maintain the proper rail fuel pressure. Changes to the flow command result in opening or closing of the fuel pump actuator to supply more or less fuel to the high-pressure pump.

Component Location:
The high-pressure fuel pump is mounted to the gear housing on the intake side of the engine.

Conditions for Running the Diagnostics:
This diagnostic runs continuously when the engine is running.

Conditions for Setting the Fault Codes:
The ECM has detected the measured fuel rail pressure is below the commanded fuel rail pressure by at least 250 bar [3625 psi] for 22 seconds.

Action Taken When the Fault Code is Active:
• The ECM illuminates the amber CHECK ENGINE lamp and/or the malfunction indicator lamp (MIL) immediately when the diagnostic runs and fails.
• The EGR valve will be closed.
• Engine torque will be reduced if the engine is operated for an extended period of time with this fault code active.

Conditions for Clearing the Fault Code:
• To validate the repair, start the engine and let it idle for 1 minute.
• The fault code status displayed by INSITE™ electronic service tool will change to INACTIVE immediately after the diagnostic runs and passes.
• The ECM will turn off the amber CHECK ENGINE lamp after the diagnostic runs and passes.
• For On-Board Diagnostics (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 fault codes, as well as extinguish the MIL for OBD applications.

Shop Talk:
The fuel system is designed to run on clean fuel. It has two fuel filters to maintain this cleanliness. Carelessness in handling and storage of fuel system components during the repair can subject the precision components to damaging debris. Before servicing any fuel system components (such as fuel lines, fuel pump, injectors, etc.) clean the fittings, mounting hardware, and area around the component to be removed. Store the components in a clean environment and keep all fuel port openings and line ends covered so that no dirt can enter.

Fault Code 2249 sets when the engine is running and measured rail fuel pressure remains at least 250 bar [3625 psi] less than the commanded pressure. Once detected, Fault Code 2249 will remain active until the engine is turned OFF or until the measured rail fuel pressure matches the commanded rail fuel pressure. When a condition exists that causes Fault Code 2249 to become active, it is typical for the fault code to become active when the engine is heavily loaded and to become inactive when the engine is lightly loaded. When Fault Code 2249 occurs, the fuel system has lost the ability to maintain rail fuel pressure.

If fuel pressure is low, check the following:
• Fuel inlet restrictions
• Fuel filter plugging
• Air in the fuel
• Fuel below the suction line in the fuel tank
• Fuel gear pump output low
• Fuel gear pump pressure regulator sticking or leaking
• High-pressure pump capacity decay (high leakage to drain from the high-pressure pump)
• Fuel rail pressure relief valve leaks to drain
• Fuel rail pressure relief valve opens (at too low of a pressure)Injector fuel circuit leaks to drain
• Pressure sensor reads more than 250 bar [3626 psi] lower than actual pressure.

If Fault Code 2249 is inactive and there are not any existing performance complaints, it is possible the vehicle was run out of fuel, or the fault code became active if the engine was not primed following fuel filter replacement. However, if the customer reports that the fault code becomes active during engine operation, the steps in this fault code diagnostic tree can be used to identify the cause and make a repair.

If the engine will not start, Fault Code 2249 becomes active during cranking, and no speed sensor fault codes exist, it is likely the engine is not developing rail pressure during cranking. Possibly, the engine is not primed, the gear pump pressure is too low, or the high-pressure fuel system components have excessive leakage to drain.

The procedures referenced in this troubleshooting tree also have checks for engine no start conditions. The steps of this fault code tree assume that the fault condition is repeatable (this does not necessarily mean that the fault code is active with the engine at idle).

The troubleshooting has been designed to isolate the problem into three categories:
• (1) Other more precise fault codes exist (example: electrical circuit fault codes).
• (2) Isolate the low-pressure system, determine if the low-pressure system functions correctly. The system must first be primed. Then, it is important to note that checks of fuel gear pump pressure and inlet restriction involve using a special service tool that causes the flow rate to increase to a rated flow. Fuel gear pump pressure and/or inlet restriction can not be accurately measured without a method of increasing the flow (i.e. using the special service tool or operating the engine at full power).
• 3) Isolate the high-pressure system; determine if the high-pressure system has high leakage. Verify the ECM calibration is correct. Check the calibration revision history found on QuickServe™ Online for applicable fixes to the calibration stored in the ECM.

Troubleshooting inactive Fault Code 2249 can be difficult. For engines with high counts of inactive Fault Code 2249, or if the troubleshooting tree has been exhausted, operate the engine on a chassis dynamometer or conduct a diagnostic road test to duplicate the fault code. Be certain to have a fuel pressure gauge installed at the pressure filter outlet side during the test. The most common causes of intermittent Fault Code 559 that are difficult to create are leaking high pressure connectors that only leak when the engine and the fuel are hot, intermittent fuel supply restrictions (such as debris floating in the fuel tank), or a fuel pressure relief valve that opens prematurely. Check the high-pressure connector and torque and tighten to specification, if necessary.

Use INSITE™ electronic service tool to log fuel system parameters during testing. If the accuracy of the fuel rail pressure sensor is being questioned, a key ON accuracy check can be performed. 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 for the fuel to depressurize to 0 bar [0 psi]. Wait at least 10 minutes after shutting down the engine to allow the pressure to decrease to a lower level. At key ON, a depressurized rail pressure sensor should read 0 ± 43 bar [624 psi].

When checking for air in the fuel, bubbles are 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 the fuel inlet restriction is not excessive, the source of air entry can be isolated to one of the following:
• Suction fuel lines
• Original equipment manufacturer (OEM) fuel lines
• Suction-side fuel filter assemblies, or standpipe(s) in the fuel tank(s).

Intermittent ECM power supply connections can cause Fault Code 2249. If the engine is running with an active Fault Code 2249 and Fault Codes 449, 1911, or 2311 are not present, check the ECM power supply for intermittent connections or battery issues. Fault Code 1117 can also be active if this fault condition exists. Verify the vehicle system voltage by monitoring battery voltage in INSITE™ electronic service tool data monitor or connecting a digital volt ohm meter to the batteries. This will help identify a potential system voltage issue. See equipment manufacturer service information for specified voltage range and troubleshooting procedures.

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