The B&B or Ball & Ball Accelerator Circuit Gone Bad

posted in: accelerator pump, Carburetor Kit | 0

checkballdischarge b&bpump check inlet





Here is the question. When I accelerate the engine bogs down, or dies.
Assuming the electrical system is OK, because the distributor advance will act the same way, so check that out also.
The first thing to do is turn the engine off and look down the bore of the carburetor. Pump the throttle and you should see a squirt of gas come out of the main discharge. This is located just under where the carburetor top mounts (see #28).
No squirt, or weak squirt indicates a blockage in the accelerator pump circuit. Remove the aluminum plug where the main discharge is located. See #27 in the illustration. This plug is included with our Carter B&B carburetor kits. Remove and clean the main discharge jet #28. Be careful removing this jet. They get stuck and will break easily and if it doesn’t come out easily, then leave it in and clean it out the best you can. Run thin wire through the jet to make sure it is clear.
Your carburetor may have an intake check ball located at the bottom of the accelerator pump well with a retainer wire holding it in the hole. If you don’t have the hole, then a check ball is not necessary here. The action of this part is as follows: When the pump returns to the top, gravity pushes fuel up through the bottom hole and lifts the check ball up, allowing the pump well to fill up with fuel. You can add some fluid into the float bowl and watch to see if this does happen. If your carburetor kit includes an aluminum check ball, then this is where it resides. If you can’t get fluid through this hole, then it is plugged up. Try blowing air through it. When accelerating this check ball will close keeping fuel from going back to the float bowl. Seat this check ball (only if not aluminum) by tapping on it with a brass drift punch.
In the bottom of the float bowl close to the accelerator pump well will be another check ball inside a small column. The column will have either a cap screw, or an aluminum plug covering the check ball (#29 & #30). This is the discharge check ball. When pressing down the pump, fuel will force this check ball off the seat allowing fuel to reach the main discharge.
Test the 2 check balls this way. Hold down the discharge check ball with a brass drift punch. With the pump well full of fluid press down on the pump. You should feel some resistance. If you suspect this ball to leak under this test, tap on the check ball with a brass drift punch to seat it. Now press down on the pump (full of fluid) and see if the fuel lifts up the discharge check ball.

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