PRINCIPLES GASOLINE/DIESEL FUEL SYSTEMS - OD1620 - LESSON 1/TASK 2
FIGURE 21. CHOKE VALVE OPERATION.
(3) Manuel Choke System (figure 22 on the following page). The
manually operated choke used to be the most common method of controlling the
choke valve. Due to emission regulations and the possible danger in use
with catalytic converters, and to technological advances in automatic choke
systems, manual choke systems are little used today. In a manual system,
the choke valve is operated by a flexible cable that extends into the
driver's compartment. As the control is pulled out, the choke valve will be
closed so that the engine can be started. As the control is pushed back in,
the position of the choke valve is adjusted to provide the proper mixture.
The following are two features that are incorporated into manual choke
systems to reduce the possibility of engine flooding by automatically
admitting air into the engine:
(a) A springloaded poppet valve that is automatically pulled open
by the force of the engine intake strokes.
(b) A choke valve that is pivoted off center on its shaft. This
will create a pressure differential between the two sides of the choke valve
when it is subjected to the engine intake, causing it to be pulled open
against the force of springloaded linkage.