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Home >> Hyundai >> 2009 >> Elantra GLS, Automatic >> Repair and Diagnosis >> Engine Performance >> System >> DTC Troubleshooting Procedures >> DTC P0300 Random/Multiple Cylinder Misfire Detected >> System Inspection >> Fuel System Inspection
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Fuel System Inspection

  1. Fuel Line Pressure Inspection
    1. Check the fuel for excessive water, alcohol, or other contaminants. Replace contaminated fuel as necessary.
    2. Install a fuel pressure gage
    3. Inspect fuel pressure with normal idle status

      Specification:  338~348kPa (3.45~3.55kg/cm2 )

    4. Is fuel pressure within the specified value?

      YES 

      • Go to  2

      NO 

    DTC P0300 POSSIBLE CAUSE TABLE

    Condition Possible Cause Suspected Area
    Fuel Pressure too low Clogged fuel filter Fuel filter
    Fuel leak on the fuel-pressure regulator that is assembled on fuel pump Fuel Pump (Fuel Pressure Regulator)
    Fuel Pressure too High Sticking fuel pressure regulator Fuel Pump (Fuel Pressure Regulator)
  2. Fuel Pressure Hold Inspection
    1. Stop the engine and check for a change in the fuel pressure gauge reading.

      Specification:  After engine stops, the gauge reading should hold for minimum 5 minutes

    2. Is fuel pressure within the specified value?

      YES 

      NO 

    DTC P0300 POSSIBLE CAUSE TABLE

    Condition Possible Cause Suspected Area
    Fuel pressure drops slowly Injector leak Injector
    Fuel pressure drops immediately Stuck open in check valve of the fuel pump Fuel pump