Massey Ferguson 157 – EEM3 or EEM4 (Electronic Engine Management): Fuel Rail Pressure High

The engine control module detects that the measured fuel pressure in the high-pressure common rail is significantly higher than the commanded (target) pressure by a calibrated limit. This condition can cause engine noise (especially at idle), rough running, and will typically force the engine into a derated (reduced power) state to protect the fuel system components.

• 4710
• 7724S
• 5712SL
• Interim Tier 4 (2012-2015)
• 7722
• 7722S
• 7615
• 5613
• 5713SL
• 7720S
• 7716
• 7718
• T4
• 7715
• 5710SL
• 7726
• 7616
• 7618
• 5608
• 4708
• 7619
• 7626
• 7726S
• 7624
• 4707
• 4709
• 5711SL
• 7614
• 7718S
• 5610
• 7620
• 7719
• 7714
• 7716S
• T4 (2015-2021)
• 5612
• 7622
• 7720
• Tier 4 (2015-2021)
• 5611
• 7715S
• 5609
• 7724
• 7700 Series

1. 1

   Check for associated codes using a diagnostic tool (like AGCO EDT). Look for SPN 157 FMI 3 or FMI 4, which indicate a circuit fault at the sensor.

2. 2

   Inspect fuel return lines from the fuel rail and high-pressure pump to the tank for restrictions or kinks that would prevent excess fuel from bleeding back.

3. 3

   Verify sensor plausibility with the key ON and engine OFF. Live data for Fuel Rail Pressure should read at or near 0 bar/psi. A high reading indicates a faulty sensor or wiring.

4. 4

   Check the Fuel Pump Actuator (Quantity Control Valve / QCV) on the high-pressure pump to see if it is mechanically stuck open or has a wiring fault causing maximum fuel delivery.

1. 1

   Wiring and Harness Inspection

   Disconnect the Fuel Rail Pressure Sensor and the Fuel Pump Actuator. Inspect the connectors for corrosion, water ingress, or bent pins. Repair any damaged wiring.

2. 2

   Clear Return Lines

   Disconnect the fuel return line and blow low-pressure compressed air through it toward the tank (ensure the fuel cap is off) to verify it is completely clear of blockages.

3. 3

   Sensor Replacement

   If the return lines are clear and the wiring is intact, but the sensor reading is erratic or falsely high (as tested in the diagnostic phase), replace the Fuel Rail Pressure Sensor.

4. 4

   Actuator / Pump Replacement

   If the sensor is reading accurately and the pressure is genuinely too high, the Fuel Pump Actuator (QCV) is failing to regulate fuel flow. Depending on the specific AGCO Power engine model, the actuator may be replaceable on its own, or you may need to replace the entire High-Pressure Fuel Pump assembly.

5. 5

   Validation

   After replacing the faulty component, clear the fault codes using your diagnostic tool. Cycle the key, start the engine, and let it idle for at least 1 minute to verify the repair. Monitor live fuel rail pressure to ensure it matches the commanded pressure.