Case IH 3925 – Engine Control Unit (ECU) / EDC (Electronic Diesel Control): Fuel pressure control Metering unit: Too low fuel rail pressure in fast transient condition with MeUn Control with empty tank.

The engine control system has detected that the fuel rail pressure dropped below the minimum required threshold during a fast transient condition alongside an empty tank condition, indicating fuel starvation on the low-pressure supply side.

• CVX
• Magnum
• Steiger
• Maxxum

1. 1

   Verify fuel level to ensure the tank is not actually empty or critically low

2. 2

   Construct and install a clear test line at the inlet of the high-pressure fuel pump and observe for air bubbles while running

3. 3

   Measure low-pressure supply by installing a pressure gauge between the fuel filter and high-pressure pump (should be a minimum of 5 bar / 72 psi)

4. 4

   Inspect the fuel pre-filter and main fuel filter for severe restrictions, and check Voss O-ring fittings for damage

5. 5

   Check the bottom and sidewalls of the fuel tank for debris or algae blocking the fuel pickup tube

1. 1

   Refuel and Prime

   If the tank is low, fill the fuel tank and prime the fuel system to eliminate the empty tank variable.

2. 2

   Replace Filters

   Remove and replace the fuel pre-filter and the main fuel filter(s).

3. 3

   Reseal Fuel Lines

   If air was observed in the clear diagnostic tubing, locate the suction leak. Replace the Voss O-rings on the fuel line connections between the tank, lift pump, and filters.

4. 4

   Clean the Fuel Tank

   If the low-pressure gauge shows a vacuum/restriction before the filters, drain the fuel tank, remove the sending unit/pickup assembly, and clean out any debris blocking the suction screen.

5. 5

   Replace the Lift Pump

   If no air is present but the low-pressure supply remains below 5 bar (72 psi) after filter replacement, replace the low-pressure fuel lift pump.

6. 6

   Address the Metering Unit

   If the low-pressure supply is verified to be perfect (no air, >72 psi) but the code persists during fast acceleration, the Fuel Metering Unit (MeUn) on the high-pressure injection pump is failing to regulate pressure and must be replaced.