GM Service Manual Online
For 1990-2009 cars only

Fuel Injector Cleaning L26 Only

Tools Required

    • J 37287 Fuel Line Shut-Off Adapters
    • J 38500-A Fuel Injector Cleaner
    • J 42873-1 3/8 Fuel Line Shut-Off Adapter
    • J 42873-2 5/16 Fuel Line Shut-Off Adapter
    • J 42964-1 3/8 Fuel Pipe Shut-Off Valve
    • J 42964-2 5/16 Fuel Pipe Shut-Off Valve

Notice: 

   • GM Upper Engine and Fuel Injector Cleaner is the only injector cleaning agent recommended. DO NOT USE OTHER CLEANING AGENTS AS THEY MAY CONTAIN METHANOL, WHICH CAN DAMAGE FUEL SYSTEM COMPONENTS.
   • Under NO circumstances should the GM Upper Engine and Fuel Injector Cleaner be added to the vehicle fuel tank, as it may damage the fuel pump and other system components.
   • Do not exceed the recommended cleaning solution concentration. Higher concentrations may damage fuel system components. Testing has demonstrated that exceeding the recommended cleaning solution concentration does not improve the effectiveness of this procedure.

Important: 

   • Vehicles with less than 160 km (100 mi) on the odometer should not have the injectors cleaned. These vehicles should have any out of specification injectors replaced.
   • During this procedure you will need a total of 960 ml (32.4 oz) of cleaning solution. That is 2 tanks of solution for the J 38500-A . Other brands of tools may have a different capacity and would therefore require more or less tanks to complete the procedure. You must use all 960 ml (32.4 oz) of solution to insure complete injector cleaning.


    Object Number: 651337  Size: SH
  1. Obtain J 38500-A (2).
  2. Important: Verify the valve at the bottom of the canister (3) is closed.

  3. Empty two of the 30 ml (1 oz) reservoirs of the GM Upper Engine and Fuel Injector Cleaner twin reservoir container into the J 35800-A , injector cleaning tank, then add 420 ml (14 oz) of regular unleaded gasoline. If you are using any other brand of cleaning tank, you will need a total of 60 ml (2 oz) of GM Upper Engine and Fuel Injector Cleaner mixed with 420 ml (14 oz) of regular unleaded gasoline.
  4. Fill the injector cleaning tank with regular unleaded gasoline. Be sure to follow all additional instructions provided with the tool.
  5. Electrically disable the vehicle fuel pump by removing the fuel pump relay and disconnecting the oil pressure switch connector, if equipped.
  6. Disconnect the fuel feed and return line (if equipped) at the fuel rail. Plug the fuel feed and return line (if equipped) coming off the fuel rail with J 37287 , or J 42964-1 , and J 42964-2 , or J 42873-1 and J 42873-2 as appropriate for the fuel system.
  7. Connect the J 38500-A to the vehicle's fuel rail.
  8. Pressurize the J 38500-A to 510 kPa (75 psi).
  9. Start and idle the engine until it stalls, due to lack of fuel. This should take approximately 15-20 minutes.
  10. Turn the ignition to the OFF position.
  11. Injectors should be flow-tested at this point. If further cleaning is needed, a repeat of the above procedure should be done.
  12. When the injector restriction returns to zero, proceed to step 12.

  13. Disconnect the J 35800-A from the fuel rail.
  14. Reconnect the vehicle fuel pump relay and oil pressure switch connector, if equipped.
  15. Remove the J 37287 , or J 42964-1 and J 42964-2 , or J 42873-1 and J 42873-2 and reconnect the vehicle fuel feed and return lines.
  16. Start and idle the vehicle for an additional two minutes to ensure residual injector cleaner is flushed from the fuel rail and fuel lines.
  17. Pour the entire contents of GM Fuel System Treatment Plus, GM P/N 88861011 (Canadian P/N 88861012) into a nearly empty tank and advise the customer to refuel with up to 76 L (20 gal) of fuel.
  18. Advise the customer to use only a Top Tier Detergent gasoline and to add a bottle of GM Fuel System Treatment Plus to the fuel tank at every oil change.
  19. Regular use of GM Fuel System Treatment Plus should keep the customer from having to repeat the injector cleaning procedure.

  20. Road test the vehicle to verify that the customer concern has been corrected.