Electric Choke Thermostat Issues

digitalexpl0it · Aug 2, 2017

I have a 1982 Ford Bronco with the stock 2 barrel carburetor. It used a heat rise pipe to warm up the choke thermostat. I switched it out for an electric choke. I noticed the S-terminal off the alternator was 7v and some reading told me it was an A/C current. Now with the new electric choke I got it needs a 12v connection. I spliced into the ignition wire which reads 12v when the key is on and attached it to the choke thermostat. When I turn the ignition on, I can feel the choke getting warm. I can turn the choke to open/close the choke for adjusting just fine. But after 15 mins the choke opens but not much. Could this be a bad thermostat out of the box? Also if I take it off and run 12v to it should I see the spring expand? I am in california so the weather has been hot 98-110, when I was working on it the weather was 102 out. Could the thermostat already be open then?

Rons beast · Aug 3, 2017

Hey digital,

The electric choke has to be grounded as well. There should be metal on the side mounted to the choke housing. Be sure the housing is clean and free of carbon or any other corrosion. The spring will expand and contract with resistance and temperature, so the ambient temps being in the 102s would definitely effect the spring.

At 102 outside and a completely cold engine, the choke should just be closed with slight pressure. (This is an estimated setting and can be adjusted for best performance).

For wiring I recommend a relay from the battery + with a fuse,(Probably 10 or 15 A) activated by the 12v from the ignition. This way if there is a short it won't blow the ignition fuse and leave you unable to run.

Ultimately the relay should be activated by oil pressure so the choke only gets power when the engine is running. However I don't have my wiring diagrams and cannot help with that at this time. Perhaps the other fine members here can help.

Good Luck

miesk5 · Aug 3, 2017

Yo,

Great stuff Ron!

yo D,

1981 Bronco/F Series Electrical & Vacuum Troubleshooting Manual (EVTM), partial by Gary

See Charge & Power Distribution Section.

It describes the S terminal having 50% of the Dc voltage of the B terminal that should have around 12.6 or more volts probably 14 volts DC.

It also describes the choke heater circuit.

Here is that section;

digitalexpl0it · Aug 3, 2017

Rons beast said:
Hey digital,

The electric choke has to be grounded as well. There should be metal on the side mounted to the choke housing. Be sure the housing is clean and free of carbon or any other corrosion. The spring will expand and contract with resistance and temperature, so the ambient temps being in the 102s would definitely effect the spring.

At 102 outside and a completely cold engine, the choke should just be closed with slight pressure. (This is an estimated setting and can be adjusted for best performance).

For wiring I recommend a relay from the battery + with a fuse,(Probably 10 or 15 A) activated by the 12v from the ignition. This way if there is a short it won't blow the ignition fuse and leave you unable to run.

Ultimately the relay should be activated by oil pressure so the choke only gets power when the engine is running. However I don't have my wiring diagrams and cannot help with that at this time. Perhaps the other fine members here can help.

Good Luck

Thanks for the information. Looking at the choke thermostat I don't see a pin or anything for the ground, it has one connector on the thermostat. Do I sodder to one of the metal brackets shown below?

Rons beast · Aug 3, 2017

Hey digital,

The metal on each side is what the manufacturer designed to be a ground. Soldering a wire for ground on one would be a great idea.

digitalexpl0it · Aug 4, 2017

Rons beast said:
Hey digital,

The metal on each side is what the manufacturer designed to be a ground. Soldering a wire for ground on one would be a great idea.

Ok thanks, looking at it closer, that's what I thought. I can try this, Was also thinking about attaching a ground to the metal bracket that attaches it to the carb but I think soddering to the thermostat would give a better connection. I will try it this weekend. thanks for the information

digitalexpl0it · Aug 7, 2017

After taking off the round brace, I cleaned it up and put it back on the choke thermostat. I checked the carb with a volt meter as the ground and the choke 12v hot end and it was grounding. After attaching the 12v connector to the TChoke everything started working. I believe the round brace was to corroded to ground. I also put in a relay as suggested with some fuses from the ignition wire. Was able to use two relays one for the e fuel pump and one for the e choke. Now back to wiring my new efans for it.

Electric Choke Thermostat Issues

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miesk5

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