Case IH 19711 – Engine Control Module (ECM): Positive deviation of rail pressure under fast condition exceeded

The actual fuel pressure in the rail is significantly higher than the target pressure requested by the computer during a rapid transient state, such as a sudden change in engine load, acceleration, or deceleration. This is typically caused by a sticking Fuel Metering Unit (MPROP), a restricted fuel return line, or a skewed rail pressure sensor.

• Tier 4b
• Puma
• Magnum
• Steiger
• Optum
• Farmall
• combines
• loaders

1. 1

   Check Fuel Return Lines: Ensure there are no kinks, blockages, or restrictions in the fuel return lines going back to the tank.

2. 2

   Low-Pressure System Test: Verify the low-pressure supply (lift pump) is delivering the correct pressure to the high-pressure pump and change the primary and secondary fuel filters to rule out flow restrictions.

3. 3

   Wiring and Connector Inspection: Inspect the wiring harness and connectors at the Fuel Metering Unit (MPROP/FCA) on the high-pressure pump and the Fuel Rail Pressure Sensor for corrosion, pushed-out pins, or chafed wires.

4. 4

   Live Data Monitoring: Using the CNH EST, monitor Actual Rail Pressure versus Commanded/Target Rail Pressure while varying the engine RPM to see if actual pressure wildly overshoots the target.

5. 5

   Sensor Plausibility Check: With Key ON, Engine OFF, check the rail pressure sensor reading; it should read at or near 0 bar/psi.

1. 1

   Relieve Fuel System Pressure

   Turn off the machine and wait for the high-pressure fuel system to depressurize before opening any lines.

2. 2

   Clear Restrictions

   If the diagnostic checks revealed a pinched or clogged fuel return line, repair or replace the affected line and retest the machine.

3. 3

   Replace the Fuel Metering Unit (MPROP)

   If the return lines are clear and the wiring is intact, disconnect the electrical connector to the MPROP, remove the mounting screws securing it to the high-pressure pump, lubricate the O-rings on the new MPROP with clean diesel fuel, install it into the pump, and torque the fasteners to OEM spec.

4. 4

   Replace the Rail Pressure Sensor

   If the sensor failed the Key ON/Engine OFF plausibility check, replace the sensor located on the fuel rail.

5. 5

   Check the Pressure Relief Valve (PRV)

   If the PRV has been triggered multiple times by severe over-pressure spikes, it may weaken and leak, requiring replacement.

6. 6

   Calibration and Testing

   Connect the CNH EST diagnostic tool, clear the 19711 fault code, and perform a test drive under varying loads to ensure the rail pressure tracks the commanded pressure accurately without spiking.