What Does that Bottom Carburetor Hose Do?

If you’re new to working on carburetors, you may come across some hoses that seemingly go nowhere, and you may ask yourself what the heck does that one hose on the bottom of a carb do anyway?

Partzilla’s powersports vehicle repair expert John Talley hosts live Q&A sessions on our YouTube channel every Friday at 3pm Eastern. In this session, John was asked what that one hose on the bottom of a carb that doesn’t seem to go anywhere is for.

Carburetor hoses

Bottom Carburetor Hose Function Q&A

Hi. I’m not very savvy when it comes to mechanical work, so this may be a dumb question but, there’s a hose at the bottom of my carburetor that doesn’t seem to go anywhere. Is this hose a drainage hose?

John Talley: Well it is, sort of. It has two purposes. One, if you want to drain the carburetor bowl, there should be a small brass slotted screw down at the bottom of the bowl. You need to open that up after you shut off the fuel petcock, and you could drain the carburetor. The other thing it does is if the float gets stuck, instead of filling up the engine with fuel, it’ll have an overflow tube which bypasses that valve, and then it’ll let it drain out. … But yes, it is a type of drainage hose as I just described. And if it’s something you didn’t already know, then it’s not a dumb question at all.