Choke Thermostat/Heater: Description and Operation
DESCRIPTIONMost carbureted engine models are equipped with an electric assist choke. This device aids in reducing emissions of hydrocarbons (HC) and carbon monoxide (CO) during starting and warm-up (choke on) period. The electric assist choke is designed to give a more rapid choke opening at temperatures of about 54° to 74° F, or higher. It also provides a slower choke opening at temperatures below this point.
The electric assist choke system does not change any carburetor service procedures and cannot be adjusted.
OPERATION
On this application, a variable voltage choke is used, which has no internal switch mechanism. The electric choke receives a pulsed battery voltage which is controlled by the EEC-IV engine computer. The power pulse can last from 0.1 to 2.5 seconds (continuous) depending on air charge temperature, engine coolant temperature, altitude and time since start.