Case IH 3141 – Engine Control Module (ECM): Fuel Metering Unit: leakage is detected based on fuel quantity balance

The Engine Control Unit has detected that the set point of fuel volume flowing through the fuel metering unit is lower than the calculated limit. This discrepancy causes the system to suspect a fuel supply restriction, a leak in the high-pressure system, or a defective high-pressure pump, typically resulting in a severe power derate.

• Farmall
• Magnum Series
• Puma Series
• Steiger / Quadtrac Series
• Compact Track Loaders / Skid Steers

1. 1

   Inspect all low-pressure fuel supply lines from the tank to the pump, paying special attention to 90-degree plumbing fittings for plastic shavings or blockages

2. 2

   Ensure the fuel tank vent (or rollover safety valve) is not stuck closed, which can create a vacuum and restrict fuel supply

3. 3

   Test low-pressure fuel supply by running the machine off a clean, portable fuel tank or installing an inline electric fuel pump to verify adequate positive pressure under load

4. 4

   Inspect low-pressure fuel return tubes from the pump back to the tank for clogs or restrictions

5. 5

   Measure injector return leakage by running the engine and checking return volume (excessive volume indicates internal injector leaks)

6. 6

   Inspect the Fuel Metering Unit (M-Prop) wiring harness and connectors for loose contacts, chafing, or shorts

1. 1

   Resolve Supply Restrictions

   If diagnostic checks reveal clogged lines, clear the blockages, drain/clean the fuel tank if plastic filings are present, and replace the primary and secondary fuel filters.

2. 2

   Replace the Fuel Metering Unit

   If the low-pressure fuel supply is verified to be perfect (no air ingress, good pressure) but the fault persists when the fuel gets hot or under load, replace the Fuel Metering Unit (also known as the high-pressure pump control solenoid).

3. 3

   Replace Leaking Injectors

   If the injector return volume test shows excessive leakage, replace the faulty fuel injectors.

4. 4

   Replace the High-Pressure Pump

   If the metering unit and injectors are functioning correctly, but the system still cannot maintain the fuel quantity balance, the high-pressure fuel pump itself is defective and must be replaced.

5. 5

   Clear Codes and Test

   Use a diagnostic tool (such as the CNH Electronic Service Tool or Jaltest) to clear the fault codes and run the machine under load to confirm the repair.