GM Service Manual Online
For 1990-2009 cars only
Makes 🢒 Chevrolet 🢒 2003 🢒 Astro - 4WD 🢒 Engine 🢒 Engine Controls - 4.3L 🢒 Fuel Injector Cleaning

Tools Required
    • J 38500-A Fuel Injector Cleaner
    • J 39021 Fuel Injector Coil/Balance Test
    • J 39021-210 Injector Switch Box
    • J 39021-301 Injector Harness Connector
    • J 41413 EVAP Pressure/Purge Diagnostic Station
    • J 44466-1 Fuel Recirculation Hose
    • J 44466-10 Regulation and Hose Assembly
    • J 44466-12 Fuel Metering Body Jumper Block
    • J 44466-13 Screws

    Object Number: 331785 Size: SH
  1. Loosen the fuel filler cap to relieve vapor pressure in the fuel tank.
  2. Remove the engine cover.
  3. Remove the resonator and air inlet duct from throttle body.
  4. Remove the brake booster vacuum hose and connector from intake manifold.
  5. Remove the electrical connector from the central sequential fuel injection (CSFI) fuel metering body.
  6. Remove the spark plug wires from 1, 3, and 5 from the distributor cap.
  7. Relieve the fuel system pressure.
  8. Disconnect fuel pipes (3) at rear of intake (1).

    9. Object Number: 334517 Size: SH
  9. Remove the fuel line bolt (4) at the rear of intake manifold.

    10. Object Number: 648217 Size: SH
  10. Remove the nuts (1) and clamp (2) from the fuel pipe.
  11. Remove fuel pipes from the metering body.

    12. Important: Make sure that the fuel pipe O-rings, washers and spacers are present and in their proper position.


    Object Number: 648221 Size: SH
  12. Install the J 44466-12 (2) and the J 44466-13 (1) to the metering body and tighten.

    13. Object Number: 648222 Size: SH
  13. Install the J 44466-1 (1) to the fuel pipe and tighten.

    14. Object Number: 648216 Size: SH
  14. Obtain the J 41413 , close the valve (2) on the tank (3) and remove the regulator assembly.
  15. Install the J 44466-10 (5) to the J 41413 tank (3).

    16. Object Number: 648224 Size: SH
  16. Connect the J 44466-10 hose (1) to the J 44466-12 (3).
  17. Install the J 39021 , the J 39021-210 , and J 39021-301 (4) to the metering body electrical connector.
  18. Adjust the amperage selector switch on the J 39021 to 0.5  amps.

    19. Object Number: 648216 Size: SH
  19. Open the valve (2) on the tank (3).
  20. Open the valve (4) on the J 44466-10 to pressurize the fuel system. Then close valve (4) before firing injectors.

    21. Important: The minimum pressure required on the gage (6) is 150 psi. If 150 psi is not obtained, the tank (3) must be refilled prior to performing this procedure.

  21. Fire one injector using the J 39021 . Observe a pressure drop on the gage (6) and verify the injector/poppet valve operation. An injector/poppet that is "stuck" and not operational will have no pressure drop on the gage. If an injector remains "stuck", repeat the procedure multiple times, as required, until the injector is operational.
  22. Repeat steps 19 and 20 for each individual injector to verify that all injector/poppet valve assemblies are unstuck and functional.
  23. Shut off pressure valve (2) on the tank (3) of the J 41413 .
  24. Bleed off the pressure at the J 44466-10 .

    25. Object Number: 648224 Size: SH
  25. Disconnect and remove the J 44466-10 (1) from the J 44466-12 (3) and the J 41413 .
  26. Remove the J 39021-301 , J 39021-210 , and J 39021 from the metering body.
  27. Install the vehicle electrical connector to the metering body.
  28. Install brake booster vacuum hose and connector to the intake manifold.
  29. Install ignition wires 1, 3, and 5 to the distributor cap.
  30. Install the resonator and air intake duct to the throttle body and hand tighten wing nut.

    31. Object Number: 651337 Size: SH
  31. Obtain J 38500-A (2).

    32. Important: Make sure the valve at the bottom of the canister (3) is closed.

  32. Remove the canister top and add Top Engine Cleaner GM P/N 12346535 to the canister.
  33. Fill the remainder of the canister with regular unleaded gasoline and install the canister top.
  34. Suspend J 38500-A from a convenient location.

    35. Object Number: 648224 Size: SH
  35. Connect the hose from J 38500-A (1) to the service port on the J 44466-12 (3).

    36. Object Number: 651337 Size: SH
  36. Open valve (3) at the bottom of J 38500-A .
  37. Connect a shop air source to the fitting at the top of J 38500-A and adjust the regulator (1) to 75 psi.
  38. Let the vehicle run at idle until the canister is empty and the vehicle stalls.
  39. Remove the shop air supply from J 38500-A .
  40. Depressurize the J 38500-A .
  41. Disconnect the J 38500-A hose from the J 44466-12 .
  42. Remove the resonator and air inlet duct from the throttle body and set aside.
  43. Remove ignition wires 1, 3, and 5 from the distributor cap.
  44. Remove brake booster vacuum hose and connector from the intake manifold.
  45. Bleed the residual pressure from J 44466-12 .

    46. Object Number: 648221 Size: SH
  46. Remove the J 44466-13 (1) and the J 44466-12 (2) from the metering body.

    47. Object Number: 648222 Size: SH
  47. Remove the J 44466-1 (1) from the fuel lines.

    48. Important: Make sure that all of the O-rings (6, 8), washers (7), and spacers (5) are present and in proper position.


    Object Number: 334517 Size: SH
  48. Install the fuel pipe (3) to the metering body.

    49. Notice: Use the correct fastener in the correct location. Replacement fasteners must be the correct part number for that application. Fasteners requiring replacement or fasteners requiring the use of thread locking compound or sealant are identified in the service procedure. Do not use paints, lubricants, or corrosion inhibitors on fasteners or fastener joint surfaces unless specified. These coatings affect fastener torque and joint clamping force and may damage the fastener. Use the correct tightening sequence and specifications when installing fasteners in order to avoid damage to parts and systems.

  49. Install the clamp (2) and nuts (1).

    50. Tighten
    Tighten nuts to 3 N·m (27 lb ft).

  50. Apply threadlock GM P/N 12345382 or equivalent to the threads of the fuel pipe bolt (4).
  51. Install the fuel pipe bolt.

    52. Tighten
    Tighten bolt to 6 N·m (53 lb ft).

  52. Install the brake booster vacuum hose and connector to the intake manifold.
  53. Install the resonator and air inlet duct to the throttle body.
  54. Install brake booster vacuum hose and connector to the intake manifold.
  55. Install ignition wires 1, 3, and 5 to the distributor cap.
  56. Install engine cover.
  57. Add one ounce of Port Fuel Injector Cleaner GN P/N 12345104 (in Canada P/N 12345515) to the vehicle fuel tank for each gallon of gasoline estimated to be in the tank.

    58. Important: Instruct the customer to add the remainder of the bottle of Port Fuel Injector Cleaner to the vehicle fuel tank at the next fill up.

    Important: Advise the customer to change brands of fuel.

  58. Hand tighten the fuel tank filler cap.
  59. Start the vehicle and check for fuel leaks.
  60. Using a Tech II scan tool, check for any stored Powertrain DTC codes. Clear codes as required.
  61. Disconnect Tech II scan tool.