The outlet you describe sounds like the float bowl drain. These should have a nipple with a hose attached that drains to the ground under the machine. Usually there's a plastic "vacuum break" at the end of the hose that allows one-way (out) flow. This prevents water from getting into the carb if you should get in that deep.
The bowl drain serves two purposes. First, loosening the screw drains the bowl as you describe. This is commonly done for off season storage or before disassembly. Second, the bowl has a standpipe that's the maximum height the fuel level in the bowl should never exceed. If the fuel level ever exceeds this, it flows into the pipe and drains out through the same hole as the bowl drain. Normally, this level is never reached as the float will have raised with the fuel level and shut off the fuel at the needle valve. The most common reason fuel drips from the overflow is because the needle valve is leaking. Don't make the mistake of trying to plug the hole as fuel will continue to leak and eventually overflow into the carburetor bore and flood the engine. My suggestion would be to first replace the needle and seat and make sure to adjust the float level properly. - MarkC
MarkC - Spokane, WA USA
"Long live the orphaned Hawkeyes and mid-size Sportsmans"
Last edited by 1of7627; 10-08-2012 at 07:26 AM.