New Holland 3807 – ECU: Fuel Metering Unit : maximum negative rail pressure deviation with metering unit on lower limit is exceeded (second stage)

This code indicates a severe overpressure condition in the high-pressure common rail fuel system. The Engine Control Unit (ECU) has commanded the Fuel Metering Unit (also known as the Fuel Control Actuator, FCA, or M-Prop) to its absolute lower limit to reduce the fuel pressure. However, the actual rail pressure is still exceeding the target pressure by a maximum negative deviation threshold. Essentially, the system is trying to drop the fuel pressure, but the mechanical or electrical components are failing to respond, leaving the pressure dangerously high.

• T6000
• T7000
• T8000
• T9000
• T6.140
• T7.250
• T8020
• T8030
• T8040
• T7040
• T7060
• CR7.80
• CR8.90
• CR9.90
• CR10.90
• CH7.70
• W170B
• W190B

1. 1

   Install a test line constructed with clear tubing at the inlet of the fuel injection pump to observe if air is entering the low-pressure fuel supply.

2. 2

   Measure the fuel pressure on the low-pressure side. If the fuel pressure drops below 0.276 bar (4.0 psi) at any time during testing under load, there is a restriction.

3. 3

   Check the primary fuel filter (operates under vacuum) and secondary fuel filter (operates under pressure) for severe restrictions or contamination.

4. 4

   The Fuel Metering Unit is a fuel-cooled solenoid valve controlled by a pulse-width modulated (PWM) signal at a frequency of 1 KHz. Check the wiring harness between the ECU and the metering unit for shorts to battery voltage, which could cause the valve to stick in a high-pressure state.

5. 5

   Verify that the Rail Pressure Sensor is reading accurately and not outputting a falsely high voltage.

1. 1

   Relieve System Pressure

   Ensure the engine is off and the high-pressure fuel system has depressurized before opening any lines.

2. 2

   Resolve Low-Pressure Restrictions

   If the diagnostic checks revealed low pressure or air, replace the fuel pre-filter and primary/secondary fuel filters. Bleed the system using the hand primer pump.

3. 3

   Inspect/Replace the Fuel Metering Unit

   If the low-pressure side is normal, the Fuel Metering Unit on the high-pressure pump is likely mechanically stuck open or failing to actuate. Remove the unit from the high-pressure pump, inspect for metal debris (which indicates pump failure), and replace the unit if faulty.

4. 4

   Inspect/Replace the Pressure Relief Valve (PLV)

   If the metering unit is functioning, the Pressure Limiter Valve on the fuel rail may be malfunctioning. Replace the PLV if it is failing to vent excess pressure.

5. 5

   Replace the Rail Pressure Sensor

   If the actual mechanical pressure is normal but the ECU is reading an overpressure condition, replace the Rail Pressure Sensor on the common rail.

6. 6

   Clear Codes

   Use the New Holland Electronic Service Tool (E.A.Sy) to clear the DTC 3807 and run the engine to verify the rail pressure matches the commanded setpoint.