Case IH F-1240-11 - ECU – Engine ECU: High pressure pump fuel delivery quantity in over run exceeds a maximum threshold

The fuel delivery has exceeded the threshold for pressure while the engine is in overrun mode. The engine control system detects that the 'Zero delivery' state is not active in the fuel metering unit, meaning there is excessive fuel flow or leakage.

• MAGNUM AFS Connect
• Magnum 235
• Magnum 245
• Magnum 275
• Magnum 305
• Magnum 335
• Magnum 340
• Magnum 400 AFS Connect
• MX Series
• TG Series
• Farmall 40
• Farmall 45
• Farmall 50
• Case CE 580 Super N
• Case CE 590 Super N

1. 1

   Verify the fault by turning the ignition key off and back on, then restarting the engine to see if the fault reactivates (may be a sensitive diagnostic function during a sudden load drop)

2. 2

   Visually inspect the engine's high-pressure fuel pipes, rail, and connections for any visible external fuel leakage

3. 3

   Check the low-pressure fuel system for clogging (especially the fuel filters) and verify the efficiency of the low-pressure feed pump

4. 4

   Perform a fuel return flow test on the injectors (cranking or running) to check for worn or contaminated injectors bypassing too much fuel

5. 5

   Test the fuel rail pressure relief valve (PRV) to see if it is leaking or popping off prematurely under normal rail pressure

6. 6

   If injectors and PRV are intact, check the fuel metering unit (FCA) on the high-pressure pump for excessive leakage or mechanical failure

1. 1

   Depressurize fuel system

   Turn off the machine and ensure the high-pressure fuel system has depressurized before opening any lines.

2. 2

   Resolve low-pressure issues

   Resolve any low-pressure fuel supply issues (replace clogged fuel filters if necessary).

3. 3

   Replace faulty fuel injectors

   If the injector return flow test reveals an injector exceeding the maximum allowable return rate, remove and replace the faulty fuel injector(s).

4. 4

   Replace pressure relief valve

   If the fuel rail pressure relief valve is leaking fuel into the return circuit during normal operation, remove the PRV from the fuel rail and install a new one.

5. 5

   Replace fuel metering unit

   If the injectors and PRV test good, locate the Fuel Metering Unit (Fuel Control Actuator) mounted on the high-pressure fuel pump. Disconnect its electrical harness, unbolt the unit, and replace it with a new metering valve.

6. 6

   Replace high-pressure fuel pump

   If replacing the metering unit does not resolve the excessive fuel delivery condition, the internal components of the high-pressure fuel pump are likely defective, and the entire high-pressure pump assembly must be replaced.

7. 7

   Reassemble and test

   Reconnect all lines, prime the fuel system with clean, filtered fuel, and use a diagnostic scan tool to clear the Engine ECU fault codes. Run the machine to verify the repair.