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Home >> Cadillac >> 2021 >> CT4 Sport, 4WD >> Repair and Diagnosis >> External Pages >> Different car >> Section 122 (Engine Controls And Fuel - 2.7L (L3B) - Diagnostic Information And Procedures (3 Of 3)) >> Diagnostic Information and Procedures >> Fuel System Diagnosis >> Circuit/System Testing

Circuit/System Testing

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Fuel Pressure Low

  1. Verify the following conditions do not exist:
      NOTE:

      If the system has recently been serviced, it is possible that air is trapped in the system causing the condition or a DTC to set.

    • Air in the system - Fuel Feed Pipe
    • Fuel Feed Pipe - Leaking/Restricted/Visible Damage
    • Fuel Strainer - Blocked/Debris/Restricted/Visible Damage
    • One-way Check Valve @ Fuel Feed Pipe - Defective/Visible Damage
    • Poor Connection @ Fuel Pump - Chassis Ground
    • Poor Connection @ Fuel Pump - Electrical Connector
    • Poor Connection @ K111 Fuel Pump Driver Control Module - Electrical Connector
    • If a condition exists 

      Repair or replace as necessary

    • Go to next step: If no conditions exist 
  2. Test or replace the component: G12 Fuel Pump

Fuel Pressure High

  1. Verify the following conditions do not exist:
      NOTE:

      If the system has recently been serviced, it is possible that air is trapped in the system causing the condition or a DTC to set.

    • Air in the system - Fuel Feed Pipe
    • Excessive Vapor - Fuel Feed Pipe
    • Fuel Feed Pipe - Kinked/Restricted/Visible Damage
    • If a condition exists 

      Repair as necessary

    • Go to next step: If no conditions exist 
  2. Test or replace the component: G12 Fuel Pump

Fuel Pressure Leaks Down

  1. Ignition/Vehicle - Off
  2. Install - CH-48027  Digital Pressure Gauge @ Schrader Valve - Fuel injector side @ CH-37287-1A  Fuel Pressure Tap and Shut-Off Adapter (3/8) - Refer to: Fuel Pressure Gauge Installation and Removal
  3. Open the valve on the tool: CH-37287-1A  Fuel Pressure Tap and Shut-Off Adapter (3/8)
  4. Ignition - On / Vehicle - In Service Mode & Engine - Off
  5. Perform the scan tool control function: Fuel Pump Enable - On
  6. Close the valve on the tool: CH-37287-1A  Fuel Pressure Tap and Shut-Off Adapter (3/8)
  7. Verify the scan tool parameter: Fuel Pressure Sensor = Pressure drops less than 70 kPa (10 PSI) within 1 min.
    • If the pressure drops 70 kPa (10 PSI) or greater 

      Locate and replace the leaking component: Q17 Fuel Injector

    • Go to next step: If the pressure drops less than 70 kPa (10 PSI) 
  8. Test or replace the component: G12 Fuel Pump

Fuel Pressure Drops Off

  1. Verify the condition does not exist:
    • Fuel Feed Pipe - Leaking/Restricted/Visible Damage
    • Fuel Strainer - Blocked/Debris/Restricted/Visible Damage
    • Poor Connection @ Fuel Pump - Chassis Ground
    • Poor Connection @ Fuel Pump - Electrical Connector
    • Poor Connection @ K111 Fuel Pump Driver Control Module - Electrical Connector
    • If a condition exists 

      Repair or replace as necessary

    • Go to next step: If no conditions exist 
  2. Test or replace the component: G12 Fuel Pump
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