Comanche 4WD L4-150 2.5L VIN H TBI (1986)
Electric Assist Choke: Description and Operation
The electric choke reduces carbon monoxide (CO) emissions during warm-up. It provides supplemental heat to the choke bi-metal to speed up choke
valve opening after the choke interior reaches a predetermined temperature.
Fig. 11 Electric choke assembly. Except 4-151 engine
4-150, 6-258 & V8-360 ENGINES
On this system Fig 11, a special tap is provided at the alternator to supply a 7 volt power supply to the electric assist choke. A thermostatic switch
within the choke cover closes when the interior of the choke cover reaches modulating temperature. This allows current to flow to the heating element
when the circuit is completed through the choke cover ground strap and choke housing to the engine. As the heating element becomes hot, heat is
absorbed by an attached metal plate which heats the choke bi-metal coil. When the engine is turned off, the thermostatic switch remains closed until the
choke cover interior modulating temperature is reached. If the engine is started immediately after shutdown and before the modulating temperature is
reached, current will immediately begin warming up the heating element to open the choke. Once the choke cover interior temperature falls below the
modulating temperature, the thermostatic switch opens and current flow to the heating element is shut off. If the engine is restarted at this time, the
electric assist function will not operate until choke cover interior reaches its modulating temperature.
