need help what is it

http://www.automotiveforums.com/vbulletin/http://i183.photobucket.com/albums/x262/bob81354/PB060016.jpg I have a 1985 s10 carb. I am trying to find out what the little black box is. Look for the red ? mark http://i183.photobucket.com/albums/x262/bob81354/PB060016.jpg