Ford LRG-423 Service Manual page 138

03-29
Auxiliary Systems
03-29
ZENITH MODEL #33 CARBURETOR OPERATION AND SERVICE (Continued)
ACCELERATING
DIAPHRAGM
PROTECTOR
VALVE
I
I
ACCELERATING SYSTEM
PPD0014
The accelerating system consists of the pump
diaphragm assembly, accelerating jet, intake check
valve, and three parts making up the refill check. The
pump is vacuum operated. In this system the pump
diaphragm is pulled against the pump spring by the
engine manifold vacuum. When the throttle is opened,
the pull on the diaphragm drops allowing the spring to
push the diaphragm against the fuel causing it to
discharge through the accelerator jet. This amount
may be varied by adjusting the travel of the pump
spring. Such adjustment is made possible by changing
the length of the diaphragm protector in the end of the
pump spring.