Accelerator Pump Adjustment
To correct for "flat spots" on acceleration, it may be necessary to measure the amount of fuel injected by the accelerator pump and to correct it. Using a suitable tool (VW 119), it will be possible to measure fuel quantity.
- Start engine and run for a brief period to insure there is sufficient fuel in the carburetor. Remove air cleaner. For carburetors without a by-pass air drilling, turn idle adjusting screw back until throttle valve is completely closed.
- Push extension pipe over injection tube in carburetor. Open choke valve and lock it in position with the plastic piece. Operate the throttle valve until fuel is ejected from the pipe. Hold glass vial under the pipe and operate throttle valve rapidly 5 or 10 times.
- Divide amount of fuel caught by 5 or 10 and compare with a specified figure of 1.3-1.6 cc/stroke. If amount varies considerably, make all the following adjustments:
- Install thicker or thinner washers between pump lever and cotter pin (thinner washer for too much fuel; thicker washer for too little fuel). Use 0.008" (0.2 mm) thick washers.
- Move cotter pin in connecting link: If injection quantity is too large, move pin to outer side; if too small, move to inner side.
- Adjust bell crank lever: If quantity is too large, adjust toward direction "1"; if too small, adjust toward direction "2".
- Finally, check direction of fuel jet; it must be on collar of discharge arm.