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Home >> Pontiac >> 2001 >> Aztek Base, AWD >> Repair and Diagnosis >> Engine Performance >> System >> Engine Controls - System & Component Testing >> Fuel System (Diesel) >> Fuel System Diagnosis - High Pressure Side >> Fuel Pressure Regulator Graphing

Fuel Pressure Regulator Graphing

  1. Set up the scan tool in the following format:
    • 1.1 Select the Data Display on the scan tool
    • 1.2 Select Engine Data 1
    • 1.3 Select the More softkey 2 times
    • 1.4 Select the Live Plot softkey
    • 1.5 Select the Engine Speed, Actual Fuel Rail Pressure, and Desired Fuel Rail Pressure parameters by highlighting each parameter and depressing the ENTER softkey
    • 1.6 Select the Accept softkey
    • 1.7 Select the More softkey, then select the Change Min/Max softkey
    • 1.8 Select the More softkey, and adjust the parameters to the following Min/Max ranges:
      • The Engine Speed Min/Max range is 0 to 1000 RPM
      • The Actual Fuel Rail Pressure Min/Max range is 1.0 to 160 MPa
      • The Desired Fuel Rail Pressure Min/Max range is 1.0 to 160 MPa
  2. Start and idle the engine
    3. Fig 1: Good Fuel Pressure Regulator Graph, 0 Miles
    GM877557Courtesy of GENERAL MOTORS CORP.

    Figure Legends

    1. Engine Speed
    2. Actual Fuel Rail Pressure
    3. Desired Fuel Rail Pressure

    Fig 2: Good Fuel Pressure Regulator Graph, 26K Miles
    GM877556Courtesy of GENERAL MOTORS CORP.

    Figure Legends

    1. Engine Speed
    2. Actual Fuel Rail Pressure
    3. Desired Fuel Rail Pressure

    Fig 3: Fuel Pressure Regulator Graph, Surging
    GM877558Courtesy of GENERAL MOTORS CORP.

    Figure Legends

    1. Engine Speed
    2. Actual Fuel Rail Pressure
    3. Desired Fuel Rail Pressure

  3. Observe the live plot for sharp changes in the Actual Fuel Rail Pressure above and below the Desired fuel rail pressure while performing one of the following actions:
    • Idling the engine.
    • Shifting the transmission from Park to Drive, and back to Park
    • Turning the steering wheel from lock to lock
    • Turning the air conditioning ON and OFF
  4. If there is a violent fluctuation in the Actual Fuel Rail pressure, as seen in the third Graphic above, replace the fuel pressure regulator.
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