LE9 Carb question

[rockable]

There is a gray plug on my Q jet that is in series with a temp switch on the coolant return neck.  What does that gray plug attach to inside the carb and how is it supposed to work?

[Captkaos]

It controls the primary fuel metering.

Whole post on Quads: http://forum.73-87chevytrucks.com/smforum/index.php/topic,11934.html