Carburetor Installation Procedures and Adjustments (2.4L Engine Models) (VW Lt 28)

Note: You will need a hand vacuum pump and a vacuum gauge to perform the following procedures. If you do not have the necessary equipment, you should entrust this work to a specialist.

Automatic choke

24. The alignment marks on the cover and the choke unit body must be aligned (see photo).



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25. If necessary, loosen the cover screws, turn it so that the marks align, and tighten the screws again.

Air damper lowering block

23. Remove the air intake elbow.

27. Set the fast idle adjusting screw to the highest cam shoulder.

28. Start the engine without touching the gas pedal.

29. Close the air damper manually.

30. If the air damper release is working properly, it should close easily until a gap of approximately 4 mm is reached. After this, resistance should begin to be felt, which will increase as the air damper closes further.



31. If the air damper closes completely without resistance, the damper lowering unit should be checked.

32. Disconnect the block vacuum hose from the carburetor and connect a vacuum pump to it.

33. Create a vacuum and check that it is maintained in the block for 2 minutes.

34. If this is not the case, the air damper lowering unit should be replaced.

Air damper starting clearance

35. Remove the air intake elbow.

36. Remove the choke block cover

37. Press the gas pedal and set the adjusting screw (B) to the highest cam ledge (A) (see Figure 13.38).



38. Using an elastic band, lightly secure the air damper control lever.

39. Connect the vacuum pump to the air damper lowering unit.

40. Create a vacuum in the block.

41. Lightly press the air damper shaft with your finger to remove any play, and check the gap between the edge of the air damper and the carburetor wall, as indicated above.

42. If necessary, adjust the gap using the screw (B) (see Figure 13.39).

Vacuum unit - leak test

43. Disconnect the vacuum hose from the carburetor and connect a vacuum pump to the hose.

44. Create a vacuum in the block and check that it is maintained for at least 2 minutes.

45. If the vacuum dissipates earlier, the vacuum block should be replaced.

Vacuum unit - checking operation

46. If the block leak test yielded positive results, a vacuum should be created in the block again.

47. Fully open the throttle valve of chamber 1. The throttle valve of chamber 2 must be opened by the vacuum block rod (see photo).



48. Replace the vacuum unit if it does not open the throttle valve of chamber 2.

Accelerator pump

49. The accelerator pump flow can only be accurately determined using a special tester and therefore this work should be entrusted to a specialist.

Starting clearance of the throttle valve chamber 2

50. The throttle stop screw has a factory adjustment and under normal conditions it is best not to touch it. If you disassembled the throttle valve assembly or replaced the gasket during the carburetor overhaul, the throttle valve of chamber 2 can be adjusted as follows.

51. The adjusting screw is located under a protective plug, which must be replaced with a new one after adjustment is completed.

52. Remove the protective plug. Open the choke fully and close the throttle valve.

53. Loosen the screw (A) so that a gap is formed between it and the throttle lever (see Figure 13.40).



54. Quickly open and close the throttle valve.

55. Turn the screw in until it just touches the throttle lever. To determine this moment, you can leave a thin sheet of paper between the screw and the lever and carefully move it to catch the moment when it is seized by the screw.

56. From this position, turn the screw another 1/4 turn.

57. Adjust idle speed and CO content in exhaust gases.