Massey Ferguson 000157.21 – ECU: Fuel Rail Pressure Is Not As Expected During Startup Or Shutdown

The Engine Control Unit (ECU) has detected a deviation between the desired fuel rail pressure and the actual fuel rail pressure measured by the sensor during engine startup or shutdown. During startup, the high-pressure fuel pump must quickly build pressure to a specific threshold for the injectors to operate; during shutdown, the pressure should dissipate in a controlled manner. This code indicates the pressure is building too slowly, failing to reach the target, or not holding as expected, which can lead to hard starting, no-start conditions, rough running, or unexpected engine shutdown.

• 4707
• 4708
• 4709
• 4710 T4
• 5608
• 5609
• 5610
• 5611
• 5612
• 5613
• 5710SL
• 5711SL
• 5712SL
• 5713SL T4
• 6612
• 6613
• 6614
• 6615
• 6616
• 7614
• 7615
• 7616
• 7618
• 7619
• 7620
• 7622
• 7624
• 7626
• 7714
• 7715
• 7715S
• 7716
• 7716S
• 7718
• 7718S
• 7719
• 7720
• 7720S
• 7722
• 7722S
• 7724
• 7724S
• 7726
• 7726S
• 8650
• 8660
• 8670
• 8680
• 8690
• 8727
• 8730
• 8732
• 8735
• 8737

1. 1

   Scan for any other active or stored fault codes related to the fuel system, electrical system, or engine sensors

2. 2

   Inspect fuel level and quality to ensure an adequate supply of clean diesel, free from water or contaminants

3. 3

   Inspect the low-pressure fuel system for cracked, kinked, or damaged lines that could restrict flow

4. 4

   Check for air ingress at fuel line connections, the fuel filter housing, and the hand primer (a hunting or rough idle often points to air leaks)

5. 5

   Inspect fuel filters for clogs or dirt, as this is a primary cause of fuel restriction

6. 6

   Verify the low-pressure fuel lift pump is functioning correctly and supplying enough fuel to the high-pressure pump

1. 1

   Bleed the fuel system

   If any part of the low-pressure fuel system was opened or air ingress is suspected, thoroughly bleed the system according to the operator's manual to remove all trapped air.

2. 2

   Test fuel rail pressure sensor

   Using a diagnostic tool, compare desired vs. actual fuel rail pressure. With key on/engine off, pressure should be close to zero (a high reading indicates a biased/faulty sensor). During cranking, actual pressure must rise.

3. 3

   Test fuel pressure relief valve (PRV)

   Locate the PRV on the fuel rail and disconnect its return line, directing it into a container. Start the engine and let it idle. There should be no fuel coming from the PRV return port at idle. If fuel flows, the PRV is leaking and must be replaced.

4. 4

   Test high-pressure pump output

   If the sensor and PRV are good, have a qualified technician test the high-pressure pump and inlet metering valve (fuel pressure regulator) output.

5. 5

   Check for excessive injector return flow

   Perform an injector return flow test to identify if one or more faulty injectors are leaking and bleeding off rail pressure, preventing it from reaching the startup threshold.