LEMON Manuals: Even more car manuals for everyone
Home >> Subaru >> 2021 >> Ascent Base >> Repair and Diagnosis (Single Page) >> Engine Performance >> System >> Engine Control System (Diagnostics) (1 Of 4) >> Diagnostic Procedure with Diagnostic Trouble Code (DTC) >> DTC P0087: Fuel Rail/System Pressure - Too Low Bank 1 >> Notes

DTC P0087: Fuel Rail/System Pressure - Too Low Bank 1: Notes

  1. - 

    DTC detecting condition: 

    Immediately at fault recognition

    Trouble symptom: 

    • Improper idling
    • Poor driving performance
    • Poor acceleration
    NOTE: After the faulty parts are repaired or replaced, perform the final check in Basic Diagnostic Procedure. Ref. to ENGINE (DIAGNOSTICS) (HDOTC)>Basic Diagnostic Procedure>PROCEDURE .
  1. CHECK FOR FUEL DELIVERY LINE LEAKAGE  .

    Visually check the fuel delivery line for leakage.

    WARNING:
    • When checking fuel delivery line during engine operation, be very careful so that one's hair, body and clothes do not touch the rotating part in the engine compartment.
    • If there is fuel leakage, the fuel can be combusted spontaneously by the engine heat, resulting in serious accident. Therefore, take extra care.
    • Prepare the necessary fire-extinguishing appliance for immediate fire fighting in case of fire.
    NOTE: Concerning the section where visible inspection is difficult, the fuel odor provides a good indication of determining the fuel leakage.

    Are there leaks from the fuel delivery line?

    Yes  : Replace the faulty fuel delivery line. Ref. to FUEL INJECTION (FUEL SYSTEMS) (H4DOTC)>FUEL DELIVERY AND EVAPORATION LINES . Ref. to FUEL INJECTION (FUEL SYSTEMS) (H4DOTC)>FUEL INJECTOR .

    No  : Go to  2.

  2. CHECK DTC  .
    1. Turn the ignition switch to ON.
    2. Using the Subaru Select Monitor or a general scan tool, read the DTC of [Engine]. Ref. to COMMON (diag)>DIAGNOSTIC TROUBLE CODE (DTC) .

    Is DTC other than P0087 displayed? (Current malfunction)

    Yes  : Check the appropriate DTC using the "Diagnostic Trouble Code (DTC)". Ref. to ENGINE (DIAGNOSTICS) (H4DOTC)>Diagnostic Trouble Code (DTC)>LIST .

    No  : Go to  3.

  3. CHECK EXPERIENCE OF RUNNING OUT OF FUEL  .

    Check if there was an experience of running out of fuel using Check List for Interview. Ref. to ENGINE (DIAGNOSTICS) (H4DOTC)>Check List for Interview>CHECK>CHECK LIST NO. 2 .

    Has the vehicle experienced running out of fuel?

    Yes  : Finish the diagnosis.

    NOTE: DTC may be stored by running out of fuel.

    No  : Go to  4.

  4. CHECK FUEL PRESSURE  .
    1. Start the engine.
    2. Using the Subaru Select Monitor, read the value of [Fuel Rail Pressure A] and [Commanded Fuel Rail Pressure A] when racing the engine.
      NOTE: For detailed operation procedures, refer to "Common (Diagnostics)". Ref. to COMMON (diag)>DATA MONITOR .

    Is the value of [Fuel Rail Pressure A] synchronized with that of [Commanded Fuel Rail Pressure A]?

    Yes  : Go to  5.

    No 

    • The value in [Fuel Rail Pressure A] does not increase: Go to  7.
    • The value in [Fuel Rail Pressure A] does not change: Replace the fuel pressure sensor. Ref. to FUEL INJECTION (FUEL SYSTEMS) (H4DOTC)>FUEL PRESSURE SENSOR .
  5. CHECK OF FUEL PUMP  .
    1. Turn the ignition switch to ON. (Engine OFF)
    2. Using the Subaru Select Monitor, select [Fuel Pump Relay] of [Active Test] to operate the fuel pump.
      NOTE: For detailed operation procedures, refer to the "Active Test". Ref. to ENGINE (DIAGNOSTICS) (H4DOTC)>ACTIVE TEST .

    Does the fuel pump emit operating sound?

    Yes  : Go to  6.

    No  : Check fuel pump circuit. Ref. to ENGINE (DIAGNOSTICS) (HDOTC)>Diagnostics with Phenomenon>FUEL PUMP CIRCUIT .

  6. CHECK FUEL PRESSURE (LOW PRESSURE SIDE)  .

    Check the fuel pressure on low-pressure side. Ref. to MECHANICAL (H4DOTC)>Fuel Pressure>INSPECTION .

    Is the check result OK?

    Yes  : Go to  7.

    No  : Check the fuel pump and fuel delivery line. Ref. to FUEL INJECTION (FUEL SYSTEMS) (H4DOTC)>Fuel Pump>INSPECTION . Ref. to FUEL INJECTION (FUEL SYSTEMS) (H4DOTC)>Fuel Delivery and Evaporation Lines>INSPECTION .

  7. CHECK FOR FUEL DELIVERY LINE LEAKAGE (HIGH PRESSURE SIDE)  .
    1. Start the engine.
    2. Using the Subaru Select Monitor, read the change in values of [Fuel Rail Pressure A] when stopping the engine.
      NOTE:
      • In order to maintain the communication with Subaru Select Monitor, turn the ignition switch to OFF, and immediately turn it to ON.
      • For detailed operation procedures, refer to "Common (Diagnostics)". Ref. to COMMON (diag)>DATA MONITOR .

    Does the value of [Fuel Rail Pressure A] decrease rapidly?

    Yes  : Go to  8.

    No  : Go to  9.

  8. CHECK HIGH-PRESSURE FUEL PUMP  .

    Check the high-pressure fuel pump. Ref. to FUEL INJECTION (FUEL SYSTEMS) (H4DOTC)>High Pressure Fuel Pump>INSPECTION .

    Is the check result OK?

    Yes  : Go to  9.

    No  : Replace the high-pressure fuel pump. Ref. to FUEL INJECTION (FUEL SYSTEMS) (H4DOTC)>HIGH PRESSURE FUEL PUMP .

  9. CHECK FOR REPRODUCTION OF FAILURE  .
    1. Turn the ignition switch to ON.
    2. Using the Subaru Select Monitor or a general scan tool, perform the clear memory of [Engine]. Ref. to COMMON (diag)>CLEAR MEMORY .
    3. Perform the corresponding inspection mode. Ref. to ENGINE (DIAGNOSTICS) (H4DOTC)>INSPECTION MODE .
    4. Using the Subaru Select Monitor or a general scan tool, read the DTC of [Engine]. Ref. to COMMON (diag)>DIAGNOSTIC TROUBLE CODE (DTC) .

    Is DTC P0087 displayed? (Current malfunction)

    Yes  : Replace the high-pressure fuel pump. Ref. to FUEL INJECTION (FUEL SYSTEMS) (H4DOTC)>HIGH PRESSURE FUEL PUMP . After replacement, go to the next step. Go to  10.

    NOTE: When the high-pressure fuel pump has been replaced in step 8, go to "CHECK FOR FUEL DELIVERY LINE LEAKAGE (HIGH PRESSURE SIDE)" without replacing the high-pressure fuel pump. Go to  11.

    No  : End.

  10. CHECK FOR REPRODUCTION OF FAILURE  .
    1. Using the Subaru Select Monitor or a general scan tool, perform the clear memory of [Engine]. Ref. to COMMON (diag)>CLEAR MEMORY .
    2. Perform the corresponding inspection mode. Ref. to ENGINE (DIAGNOSTICS) (H4DOTC)>INSPECTION MODE .
    3. Using the Subaru Select Monitor or a general scan tool, read the DTC of [Engine]. Ref. to COMMON (diag)>DIAGNOSTIC TROUBLE CODE (DTC) .

    Is DTC P0087 displayed? (Current malfunction)

    Yes  : Go to  11.

    No  : End.

  11. CHECK FOR FUEL DELIVERY LINE LEAKAGE (HIGH PRESSURE SIDE)  .
    1. Start the engine.
    2. Using the Subaru Select Monitor, read the change in values of [Fuel Rail Pressure A] when stopping the engine.
      NOTE:
      • In order to maintain the communication with Subaru Select Monitor, turn the ignition switch to OFF, and immediately turn it to ON.
      • For detailed operation procedures, refer to "Common (Diagnostics)". Ref. to COMMON (diag)>DATA MONITOR .

    Does the value of [Fuel Rail Pressure A] decrease rapidly?

    Yes  : Replace the fuel injector. Ref. to FUEL INJECTION (FUEL SYSTEMS) (H4DOTC)>FUEL INJECTOR .

    No  : Repair the poor contact of ECM connector.

scientia non olet · About LEMON Manuals