Case IH 3920 – Engine Control Unit (ECU) / EDC (Electronic Diesel Control): Fuel pressure control Metering unit: Tool low fuel rail pressure concerning the fuel feeding with MeUn Control with empty Tank

This code indicates that the fuel rail pressure has dropped below the minimum required threshold during operation, specifically when the fuel tank is empty or running very low. The Engine Control Unit detects that the Fuel Pressure Control Valve (Metering Unit / MeUn) is unable to maintain adequate rail pressure, which is usually caused by air entering the fuel system, a severe fuel restriction, or a failing metering unit/high-pressure pump.

• Puma 125
• Puma 130
• Puma 140
• Puma 150
• Puma 165
• Puma 200
• Puma 215
• Puma 230
• Magnum 180
• MXU 110
• MXU 125
• MXU 135
• Farmall series
• AFX8010
• 5130
• 7010
• 7120
• 7230
• 8010
• 9010
• 9120
• 521E
• 521F
• 621E
• 621F
• 721E
• 721F
• 821E
• 821F
• 580SN
• 590SM
• 590SN
• 1150K
• 1650L
• 1850K

1. 1

   Verify fuel level to ensure the fuel tank is not actually empty or critically low, which naturally starves the metering unit.

2. 2

   Visually inspect the fuel tank, bottom/sidewalls, and Voss O-ring fittings for damage, blockages, or leaks.

3. 3

   Perform a clear tubing test by installing a clear test line at the inlet of the Bosch high-pressure fuel injection pump. Run the engine to observe if air bubbles are moving through the fuel system (steady streams indicate an air leak on the suction side).

4. 4

   Perform a low-pressure supply test by installing a pressure gauge between the fuel filter and the high-pressure pump. Pressure should be a minimum of 5 bar (72 psi) loaded or unloaded. Drops below 0.276 bar (4.0 psi) indicate a severe restriction or lift pump failure.

5. 5

   Inspect the fuel pre-filter (if equipped) and primary fuel filters for clogging or water contamination.

1. 1

   Resolve restrictions and air leaks

   If the clear tubing test reveals air or low pressure, replace the primary and secondary fuel filters. Clean the fuel tank and lines as required. Bleed the fuel system completely.

2. 2

   Test the Metering Unit (FCA/FPR)

   If supply pressure is good (5 bar/72 psi) but rail pressure remains too low, the Fuel Pressure Control Valve (Metering Unit) is likely sticking or failing. Unplug the sensor to see if the pump defaults to maximum pressure. If the engine starts and knocks loudly, shut it off immediately—this confirms the pump can build pressure and the metering unit is the culprit.

3. 3

   Replace the Metering Unit

   Remove the defective fuel pressure control valve from the CP3 high-pressure pump and install the replacement unit. Lubricate the O-rings with clean diesel fuel prior to installation.

4. 4

   Replace the High-Pressure Pump

   If replacing the metering unit does not restore rail pressure, the Bosch CP3 high-pressure injection pump has failed internally and must be replaced as an assembly.

5. 5

   Clear codes and verify repair

   Use a diagnostic tool to clear the EDC fault codes and test-run the machine under load to verify the repair.