GM Service Manual Online
For 1990-2009 cars only

Fuel System Cleaning Purging the Fuel Tank

Purge the fuel tank before being serviced.

Removal Procedure

  1. Remove the fuel tank from the vehicle.
  2. • Refer to Fuel Tank Replacement (Passenger/Cargo Van) for the Passanger/Cargo Van.
    • Refer to Fuel Tank Replacement (Commercial/RV Cutaway) for the Commercial/RV Cutaway Van.
  3. Remove the fuel gage sender and pump unit. Refer to Fuel Sender Assembly Replacement (2nd design) .
  4. Remove all remaining fuel from the tank.
  5. Inspect the fuel tank for any remaining fuel.

Installation Procedure

  1. Install tap water into the tank.
  2. • Move the tank to the flushing area (wash rack).
    • Agitate the water vigorously and then drain it.
  3. Install a gasoline emulsifying agent into the tank. Use an available emulsifying agent, such as Product-Sol No. 913 or the equivalent.
  4. Add water to the fuel tank.
  5. • Refer to the emulsifying agent specifications for the mixture ratio.
    • Fill the tank with water until it overflows.
    • Agitate the mixture for ten minutes.
    • Drain the tank completely.
    • Completely flush out any remaining mixture.
    • Drain the fuel tank.
    • Use an explosion meter (if available) to check for a negative reading.
    • Perform the required service work.
  6. Install the fuel gage sending and pump unit. Refer to Fuel Sender Assembly Replacement (2nd design) .
  7. Install the fuel tank into the vehicle.
  8. • Refer to Fuel Tank Replacement (Passenger/Cargo Van) for the Passanger/Cargo Van.
    • Refer to Fuel Tank Replacement (Commercial/RV Cutaway) for the Commercial/RV Cutaway Van.

Fuel System Cleaning Purging Feed and Return Pipes

Removal Procedure

  1. Disconnect the fuel feed and return pipes at the fuel injection unit. Refer to Fuel Hose and Pipes (Engine Fuel Pipes) for V6. Refer to Fuel Hose and Pipes (Engine Fuel Pipes) for V8.
  2. Important: 

       • Inspect the in-line fuel filter for contamination.
       • Replace the fuel filter if it is plugged.

  3. Disconnect the in-line fuel filter. Refer to In-Line Fuel Filter Replacement (Non-Cartridge Type) . Refer to In-Line Fuel Filter Replacement (Cartridge Type ) .
  4. Important: 

       • Use only oil free compressed air to blow out the fuel pipes.
       • If the in-line fuel filter is plugged, inspect the fuel tank internally and purge if necessary.

  5. Clean the fuel lines by applying air pressure in the opposite direction of fuel flow.

Installation Procedure

  1. Install a new strainer (if necessary) on the fuel sender assembly. Refer to Fuel Sender Assembly Replacement (2nd design) .
  2. Notice: Do not fold or twist the strainer when installing the sending unit. This action restricts fuel flow.

  3. Install the fuel sender assembly with a new seal into the fuel tank.
  4. Install the fuel tank.
  5. • Refer to Fuel Tank Replacement (Passenger/Cargo Van) for the Passanger/Cargo Van.
    • Refer to Fuel Tank Replacement (Commercial/RV Cutaway) for the Commercial/RV Cutaway Van.
  6. Disconnect the fuel feed pipe at the fuel injection unit.
  7. Connect a hose to the fuel feed pipe at the fuel injection unit. Insert the other end of the hose into a 3.8 liter (one gallon) fuel can.
  8. Connect the negative battery cable.
  9. Add twenty-three liters (six gallons) of clean fuel into the fuel tank.
  10. Purge the fuel pump and lines.
  11. Using a fused jumper, connect the fuel pump test terminal to B+ to operate the fuel pump. Operate the fuel pump until 2 liters (1/2 gallon) flows into the fuel can.
  12. Remove the jumper.
  13. Connect the fuel line at the fuel injection unit.
  14. Check for fuel leaks
  15. 12.1. Turn the ignition ON for 2 seconds.
    12.2. Turn OFF the ignition for 10 seconds.
    12.3. Again, turn the ignition switch to the ON position.
    12.4. Check for fuel leaks.