Accelerator Pump Assembly

Check operation as follows: Pour clean unleaded gasoline into carburetor bowl approximately 1/2" deep. Operate accelerator pump plunger several times to expel air from pump passage. Using a small brass rod, hold discharge check ball down firmly on its seat. See Fig 3 .

Fig 1: Exploded View of Carter Model BBD 2-Barrel Carburetor

Fig 2: Installing Accelerator Pump Intake and Discharge Check Balls Large check ball is installed in float bowl.

Fig 3: Testing Accelerator Pump Intake and Discharge Hold discharge check ball down on its seat.
Again raise plunger and press downward. No fuel should be emitted from either intake or discharge passage. If fuel does escape from either passage, check that ball seat is not damaged or dirty. Clean passages and retest.
If leakage is still present, attempt to form a new seat. This is accomplished by installing a discharge check ball in leaking seat. Place a piece of drill rod on top of check ball and tap it lightly with a hammer to form a new seat. Remove check ball and discard. Install a new check ball and retest as described above. If service does not correct problem, carburetor replacement is necessary.