SgtSkip

I know that there's a choke heater relay and, from what I can tell from searching other posts, there is supposed to be power to the choke heater when the alternator is charging. I have seen posts stating that there is voltage to the heater when the ignition is turned on but the engine is not running so I'm nopw not sure what to believe.

With that said, what exactly does the choke heater do? Does it close the choke when energized? I knwo that the choke is supposed to slowly open but how does that work? My choke is inop. and I have not been able to read a 12v signal at any time.

hydric

from my small knowledge the choke heater heats up some bi-metallic spring inside which after some time, moves the choke plate.

the power feed is from the ignition meaning when you turn they key on, the heater should start its attention on the spring.

Apeiron

That's incorrect, the choke only receives power when the engine is running and the alternator is charging.

hydric

wow i was told otherwise back then... oh well, cant be right all the time, thanks for correcting me and now i know.

SgtSkip

But what is the heated choke heater used for and what is the sequence of operation???

anubiscougar

what about those chokeless carbs?

five7kid

iTrader: (14)

2nd thing first:
1) Engine and choke are cold. Choke thermostat is applying force to the choke butterfly in the closed direction. Butterfly isn't completely closed because the high idle cam is keeping it from closing all the way.
2) You get in the car, tap the throttle and the butterfly snaps shut and the high idle cam is engaged.
3) You start the engine and the alternator starts putting out higher voltage than the battery. The choke relay closes, applying power to the choke thermostat. The choke pull-off engages due to engine vacuum, opening the choke butterfly slightly.
4) The power on the choke thermostat warms the bimetal coil, reducing the closing force on the choke butterfly and gradually opening the butterfly completely. As the throttle is applied, the high idle cam steps down until completely disengaged.

The heated choke opens the choke quicker than ambient heat from the engine would. Other methods employed in the past include hot air from a tube heated by exhaust gases, and having the choke coil sitting on the intake manifold above the exhaust cross-over passage.

Chokeless carbs are babied using the accelerator pump as the mixture enrichening device until the engine warms up enough to run on operating temperature mixtures.

Apeiron

Don't forget the hot water chokes, or chokes that used combinations of methods like the electrically-assisted hot air chokes.

SgtSkip

Way cool! Another mystery for me is solved. Thanks for the info Five7. So if my choke is not getting the required voltage then it should never open. I need to check my choke adjustment and make it right. Currently it stays wide open without any heater trons.