Case IH 3176 (F-1240-11) - ECU – Engine Control Unit (ECU) / EDC (Electronic Diesel Control): High pressure pump fuel delivery quantity in over run exceeds a maximum threshold

During an overrun condition (when the tractor is decelerating or coasting and the engine should be cutting off fuel delivery), the fuel metering unit fails to achieve its zero delivery state. The Engine Control Unit detects that the fuel rail pressure or delivery quantity is higher than the commanded set point. This is typically caused by excessive internal leakage in the fuel metering unit, a leaking fuel rail pressure relief valve (PRV), or worn fuel injectors returning too much fuel.

• VESTRUM CVX
• Magnum series (235-340 Series 4)
• Steiger series (350-600)
• Farmall series (115U)
• Maxxum models
• Case 580N Backhoe Loader
• Case 580SN Backhoe Loader
• Case 590SN Backhoe Loader
• Case 721F Wheel Loader
• Case 821C Wheel Loader
• Case 921C Wheel Loader

1. 1

   Inspect the wiring harness and connectors to the fuel metering unit on the high-pressure pump for loose contacts, shorts to battery, or shorts to ground.

2. 2

   Check the fuel rail pressure relief valve (PRV) to ensure it is not stuck open or leaking fuel back into the return line during operation.

3. 3

   Perform a leak-off (return flow) test on the fuel injectors to identify worn injectors with excessive return leakage.

4. 4

   Ensure there are no clogs in the main fuel filter or the return tubes from the pump to the tank.

1. 1

   Address Leaks

   If the injector return flow test reveals excessive leakage in one or more cylinders, replace the faulty fuel injector(s).

2. 2

   Replace the PRV

   If the fuel rail pressure relief valve is found to be leaking or stuck open, depressurize the fuel system and replace the valve.

3. 3

   Replace the Fuel Metering Unit / High-Pressure Pump

   If the wiring is intact, the PRV is holding pressure, and the injectors are not leaking, the fault lies within the high-pressure pump's fuel metering unit (excessive internal leakage preventing zero delivery). Depending on the specific Bosch CP3/CP4 pump variant, replace either the fuel metering unit itself or the entire high-pressure fuel pump assembly.

4. 4

   Relearn / Clear Codes

   After replacing the EDC, pump, or injectors, use the CNH EASy diagnostic service tool to clear the fault codes, prime the fuel system, and restore any self-learning parameters or IMA injector programming.