Accelerating Pump System - Ford LRG-423 Service Manual

03-28
Auxiliary Systems
03-28
ZENITH MODEL #33 CARBURETOR OPERATION AND SERVICE (Continued)
Accelerating Pump System
The accelerating pump controls the amount of fuel that
is discharged into the air stream on sudden throttle
openings. When the throttle is opened suddenly, air
rushes through the carburetor into the intake manifold
and to the engine. This air is lighter than the liquid fuel
and gets into motion more quickly. That means that the
air reaches the cylinders of the engine before the first
charge of fuel supplied by the high speed system.
A lean mixture would result momentarily in this case,
and to counteract the condition, additional fuel must be
supplied instantly. The supply of that extra fuel is the
job of the accelerating pump system.