Case IH F-519744-18 - ECU – Engine Control Unit (ECU): Fuel rail pressure has exceeded maximum positive deviation limits

The actual fuel pressure in the common rail system is significantly higher than the pressure commanded by the system, pointing to a fuel metering, sensor, or pressure relief issue.

• MAGNUM AFS Connect
• Magnum
• Steiger
• Puma
• Maxxum
• Farmall
• Axial-Flow Combines (240 Series)

1. 1

   Inspect the high-pressure fuel system for internal or external leakages

2. 2

   Check the engine oil level for increases or signs of fuel dilution, which indicates a fuel system leak into the oil sump (e.g., leaking injectors or rail)

3. 3

   Inspect the low-pressure system for clogging, paying special attention to the fuel filters and the tubing between the pre-supply pump and the gear pump

4. 4

   Verify the feeding of the pre-supply pump, as flow may be low due to clogged tubes at the tank outlet

5. 5

   Check for air in the fuel system

6. 6

   Test the high-pressure fuel pump for efficiency, check the fuel injectors for tightness, and verify the condition of the fuel rail pressure sensor and its wiring

1. 1

   Address Filters and Air

   Inspect and replace the fuel filters if they are clogged or dirty. Bleed the fuel system properly to ensure no air is trapped in the lines.

2. 2

   Resolve Leaks and Oil Contamination

   If fuel lines or connections are leaking, repair or replace them. If the engine oil is contaminated with fuel (oil level increased), replace the engine oil immediately to prevent viscosity breakdown.

3. 3

   Test/Replace the Fuel Rail Pressure Sensor

   If the sensor is providing erratic or incorrect high-pressure readings, replace the defective fuel rail pressure sensor.

4. 4

   Inspect/Replace the Pressure Relief Valve (PRV)

   The PRV regulates fuel pressure within the high-pressure fuel rail. If the system has experienced extreme over-pressure situations, the PRV may have reached its maximum allowed opening count or failed. Replace the PRV if necessary. Note: Installation requires extreme cleanliness, as microscopic contamination can destroy common rail components.

5. 5

   Replace the Fuel Pump

   If the fuel pump is malfunctioning or has insufficient performance after the above checks, replace the fuel pump.