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Accelerator Pump Quick Test

  • Warm up your engine
  • Turn it off
  • Remove air cleaner
  • Choke valve should be open – if not it could be stuck on the fast idle. Open the throttle a small amount which may allow it to open.
  • Pump your throttle to wide open watching the inside of the carburetor bore.
  • You should immediately see a stream, or streams of gas squirting in the throat. 1 barrel will have 1 stream, 2 & 4 barrels will have 2 streams. Some 4 barrels will pump gas in both primary & secondary bores. These will have 2 accelerator pumps.

Possible issues:

  • Main discharge could be missing the check valve (check ball, or check weight)
  • Passage from the pump well to the main discharge may be plugged.
  • Accelerator pump well may not be filling up completely.
    • Check valve is dirty, or missing (check ball usually). Some carburetors don’t use a check valve. They are filled over the top of the accelerator pump well.
  • Accelerator pump deteriorated, or it’s the wrong pump.
  • Accelerator pump installed incorrectly.
Click on image to get parts for the AFB/AVS
Updated on 10/05/2021

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