Case IH 3140 – Engine ECU: Metering Unit Signal Range Check - Signal Too Low

Fault code 3140 indicates a problem with the Fuel Metering Unit (also known as the Fuel Pressure Control Valve, MPROP, or FCA) located on the high-pressure fuel pump. A Signal Too Low condition means the electrical signal returning from the metering unit to the controller has dropped below the minimum expected voltage threshold. This typically points to a short to ground, an open circuit in the wiring harness, or a failed solenoid coil inside the metering unit itself.

• Farmall
• Case IH Magnum 235 – 340 (Series 4)
• Machines equipped with NEF Engines
• Machines equipped with F5H Engines

1. 1

   Inspect the wiring harness and connector at the Fuel Metering Unit for chafing, corrosion, or a short to ground

2. 2

   Check the fuel lines for any blockages or pinched hoses causing fuel inlet or return restriction

3. 3

   Check for air entering the fuel supply system

4. 4

   Verify the fuel delivery performance of the gear supply (lift) pump

5. 5

   Check the pressure control of the high-pressure pump inlet regulator and verify the fuel supply pressure reaching the high-pressure pump

1. 1

2. 2

   Inspect wiring

   Disconnect the electrical connector at the Fuel Metering Unit on the high-pressure fuel pump. Inspect the pins for damage or corrosion. Use a multimeter to check the harness for continuity to the Engine ECU and ensure there is no short to ground.

3. 3

   Test the solenoid

   Measure the resistance across the pins of the Fuel Metering Unit. If the coil is open or shorted internally, the unit must be replaced.

4. 4

   Remove defective unit

   If the wiring is sound but the fault persists (or the valve fails the resistance test), remove the defective Fuel Metering Unit from the high-pressure fuel pump.

5. 5

   Install new unit

   Lubricate the O-rings on the new Fuel Metering Unit with clean diesel fuel, insert it into the pump, and torque the mounting fasteners to OEM specifications.

6. 6

   Clear codes and verify

   Reconnect the wiring harness, turn the key on, and use a diagnostic tool to clear the 3140 fault code. Run the engine to verify the repair and ensure proper fuel rail pressure.