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Home >> Chevrolet >> 2021 >> Blazer RS, FWD >> Repair and Diagnosis >> External Pages >> Different variant/trim >> Section 12 (Engine Controls And Fuel - 2.0L (LSY) - Diagnostic Information And Procedures (2 Of 2)) >> 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:
    • Poor Connection @ Fuel Pump - Chassis Ground
    • Poor Connection @ Fuel Pump - Electrical Connector
    • Fuel Feed Pipe - Leaking/Restricted/Visible Damage
    • Fuel Strainer - Blocked/Debris/Restricted/Visible Damage
    • One-way Check Valve @ Fuel Feed Pipe - Defective/Visible Damage
    • 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:
    • Air in the system - Fuel Feed Pipe
    • Excessive Vapor - Fuel Feed Pipe
    • 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. Perform the following procedure/test: Fuel Pressure Relief
  3. Install - EN-37287 Fuel Line Shut-Off Adapter @ Fuel Feed Hose & Fuel Pump Fuel Feed Hose
  4. Open the valve on the tool: EN-37287 Fuel Line Shut-Off Adapter
  5. Ignition - On/Vehicle - In Service Mode & Engine - Off
  6. Perform the scan tool control function: Fuel Pump Enable - On
  7. Close the valve on the tool: EN-37287 Fuel Line Shut-Off Adapter
  8. Verify the scan tool parameter: Fuel Pressure Sensor = Pressure drops less than 34 kPa (5 PSI) within 1 min.
    • If the pressure drops 34 kPa (5 PSI) or greater 

      Locate and replace the leaking component: Q17 Fuel Injector

    • Go to next step: If the pressure drops less than 34 kPa (5 PSI) 
  9. Test or replace the component: G12 Fuel Pump

Fuel Pressure Drops Off

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