PRINCIPLES GASOLINE/DIESEL FUEL SYSTEMS - OD1620
- LESSON 1/TASK 2
(5) Providing Automatic Choke Heat. The four methods of providing
controlled heat to the automatic choke thermostatic spring are:
(a) Electricity (figure 24). A large portion of the vehicles
currently produced use an electric coil to heat the thermostatic coil
spring. The heating coil is switched on with the ignition switch. Some
systems employ a control unit that prevents power from reaching the electric
coil until the engine compartment reaches a desired temperature.
FIGURE 24. ELECTRIC CHOKE.
(b) Engine Coolant (figure 25 on the following page). Another
method of heating the thermostatic coil is to circulate engine coolant
through a passage in the thermostat housing.
(c) Intake Manifold Crossover (figure 26 on the following page).
One of the most popular methods of providing choke heat, until recent years,
is to utilize exhaust heat. The usual way of doing this is to mount the
choke mechanism containing the thermostatic coil in a molded well on the
intake manifold over the crossover passage. The choke mechanism then
operates the choke valve through linkage.
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