Recently acquired a Mule 550 (KAF300C) in non-running condition. Luckily, the main problem seemed to be a REALLY dirty fuel system and I have the thing running now after pressure-washing the inside of the tank and blowing all the debris out of the fuel pick-up tube. (Previous owner thought it was a bad fuel pump - but that pump works fines once it doesn;t have to draw against a plugged line!)

Anyway, it starts OK and even idles after a little Gumout spray carb cleaner (float bowl was surprisingly clean, float free & needle & seat functioning).

That said, there is a line coming from the carburetor that is plugged with bolt and just hanging there. I have a (PDF) manual, but the photos aren't very clear and no textual description of this line.

The line comes off the top of the carb JUST ahead of the throttle shaft (right about under the idle speed screw). This NOT The fuel line and not the "breather" that goes to the valve cover. I can't find any open port, so I'm at a loss.

Any help appreciated!