FORD MOTORCRAFT ACCELERATOR PUMP 1bbl. This is For all model 1100 Autolite and Motorcraft carburetors. These diaphragms may be found on Mustang and Comet 6 cylinder carburetors. Because Some of these carbs will require 2 of these diaphragms. As a result, One will be the accelerator pump and the other is the dashpot. Ford replacement part covers C3AZ-9B559-A. This is A must have part during a rebuild because it can cure hesitations in your Ford 1bbl carburetor.