GM Service Manual Online
For 1990-2009 cars only
Makes 🢒 GMC_Truck 🢒 1999 🢒 GMC K Sierra - 4WD 🢒 Engine 🢒 Engine Controls - 4.8L, 5.3L, and 6.0L 🢒 Fuel System Cleaning

Fuel Tank Cleaning

Important: 

   • Only use oil free compressed air to blow out the fuel pipes.
   • Inspect the fuel tank internally and clean the fuel tank if you find a plugged fuel filter.

  1. Disconnect the negative battery cable. Refer to Battery Negative Cable Disconnection and Connection in Engine Electrical.
  2. Relieve the fuel system pressure. Refer to Fuel Pressure Relief .
  3. Drain the fuel tank. Refer to Fuel Tank Draining .
  4. Remove the fuel tank. Refer to Fuel Tank Replacement .
  5. Remove the fuel sender assembly. Refer to Fuel Sender Assembly Replacement .
  6. Inspect the fuel pump strainer. Replace a contaminated strainer and inspect the fuel pump. Refer to Fuel Pump Strainer Replacement .
  7. Inspect the fuel pump inlet for dirt and debris. Replace the fuel pump if you find dirt or debris in the fuel pump inlet. Refer to Fuel Tank Fuel Pump Module Replacement .

    8. Important: When flushing the fuel tank, handle the fuel and water mixture as a hazardous material. Handle the fuel and water mixture in accordance with all applicable local, state, and federal laws and regulations.

  8. Flush the fuel tank with hot water.
  9. Pour the water out of the fuel sender assembly opening. Rock the tank to be sure that removal of the water from the tank is complete.
  10. Remove the fuel rail assembly. Refer to Fuel Injection Fuel Rail Assembly Replacement .
  11. Drain the fuel from the fuel rail. It will be necessary to remove the fuel injectors from the fuel rail to properly clear all debris from the fuel rail and fuel injectors. Use light shop air to remove any debris from the fuel rail and injectors.
  12. Replace the fuel injector O-rings.
  13. Use light shop air in the opposite direction of the fuel flow in order to remove any debris from the fuel lines. Catch any fuel from the fuel lines with an approved gasoline container.
  14. Install the injectors to the fuel rail.
  15. Install the fuel rail assembly onto the engine. Refer to Fuel Injection Fuel Rail Assembly Replacement .
  16. If equipped with a serviceable fuel filter, replace the fuel filter. Refer to In-Line Fuel Filter Replacement .
  17. Install the fuel sender assembly. Refer to Fuel Sender Assembly Replacement .
  18. Install the fuel tank. Refer to Fuel Tank Replacement .
  19. Refill the fuel tank.
  20. Install the fuel filler cap.
  21. Connect the negative battery cable. Refer to Battery Negative Cable Disconnection and Connection in Engine Electrical.

    22. Important: If the fuel pump or sender assembly was not replaced, purge the fuel sender assembly.

  22. Purge the fuel sender assembly.
    23. 22.1. Disconnect the fuel feed line from the fuel filter. Refer to In-Line Fuel Filter Replacement .
    22.2. Connect a length of hose to the fuel feed pipe.
    22.3. Insert the other end of the hose into an empty 3.8 liter (1 gallon) approved gasoline container.
    22.4. Add 23 liters (6 gallons) of clean fuel into the fuel tank.
    22.5. Turn on the fuel pump using the scan tool until 2 liters (1/2 gallon) of fuel flows into the fuel container.
  23. Inspect for leaks.
    24. 23.1. Turn the ignition switch ON for 2 seconds.
    23.2. Turn the ignition switch OFF for 10 seconds.
    23.3. Turn the ignition switch ON.
    23.4. Inspect for fuel leaks.