Case IH 3918 – 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

This code indicates that the fuel rail pressure is dropping below the minimum required limit during a fast transient event (such as rapid acceleration or a sudden, heavy increase in engine load). The system detects that the Fuel Metering Unit (MeUn) is unable to maintain the commanded high-pressure fuel rail target when the engine demands a sudden spike in fuel volume.

• Magnum
• Steiger
• Maxxum
• Farmall
• Case wheel loaders

1. 1

   Check for air ingress by installing a clear test line between the low-pressure supply and the high-pressure pump to observe for air bubbles while running

2. 2

   Test low-pressure fuel supply between the fuel filter and the inlet to the high-pressure pump (minimum 5 bar / 72 psi with engine loaded or unloaded)

3. 3

   Test vacuum restriction between the inlet of the low-pressure (lift) pump and the fuel tank (must not exceed 127 mm / 5 inches of Hg)

4. 4

   Inspect the fuel pre-filter, main fuel filter(s), and Voss O-ring fittings for physical leaks or restrictions

5. 5

   Inspect the fuel tank bottom and sidewalls for debris that could intermittently block the pickup tube during high fuel demand

1. 1

   Resolve Low-Pressure Restrictions

   If vacuum is too high or supply pressure is below 5 bar (72 psi), replace the fuel pre-filter and main fuel filters.

2. 2

   Clean the Fuel Tank

   If debris is found in the tank or the pickup tube is clogged, drain and clean the fuel tank.

3. 3

   Seal Air Leaks

   If air is observed in the clear test line, inspect and replace the Voss O-ring fittings and check the lift pump and fuel lines for ingress points.

4. 4

   Address High-Pressure Components

   If the low-pressure supply is delivering 5 bar (72 psi) of solid fuel (no air) to the high-pressure pump, replace the Fuel Metering Unit (MeUn) (also known as the Fuel Pressure Control Valve or FCA). If the issue persists, verify the accuracy of the Fuel Rail Pressure Sensor and check the high-pressure pump itself for internal wear.