Electric Choke Operation

[scottso]

I'm trying to track down a hard (cold only) start condition. It is only after several days or more - and the only way to get her to fire up is with starting fluid - or what I tried this weekend -partially restricting the air intake. So I am wondering about the choke. I unplugged it - and probed the connector. I thought I was looking for 12v on the harness side when when ignition was on. I seem to have nothing.
One wire is black (ground and its good). The other is yellow/red. Am I missing something?

[CreoRacing]

My schematic shows the Y\R wire going straight to the "main switch" - ignition sw, therefore should be hot when on. If the main fuse near the battery is good, which would make the red wire at the ign switch hot, I'd say a bad ign sw. I suppose you could always try a jumper wire(red to Y\R or B+ to Y\R) before your next cold start. Good luck and let me know how it turns out.

[scottso]

I'll give it a shot, thanks. Gonna be tough to jump that plug, it's tiny. I have a rough idea how this works, but I am not clear. I understand that there is a needle blocking or opening a port and it is open or closed based upon the "choke" heating up from the applied voltage. What I am not sure about is the principle behind it. Is the port open (needle up) to choke - and is that permitting more fuel flow? Does anyone understand the proper operation of this unit?

[scottso]

Wow, nobody knows how this operates?

[CreoRacing]

I just don't think anyone has taken the time figure it out, due to the fact that aftermarket carbs (with manual chokes) are cheap and way more reliable.
It sure sounds like you're on the right track, though.

[bradrenea]

The needle blocks the port during normal (warm) operation. When the choke is actuated it raises the needle, opening the port, allowing a richer AFR.