Toro 724 Snowblower Carburetor Work

I bought a Toro 724 Snowblower model 38050, SN 2733 (1980 model), and I've been working on it for most of the winters since I got it a couple years ago. It's better now than it was, but it still gives me fits.

This year, since I failed to store it properly, I had to pull the carburetor apart to clean out the old gelled fuel. It's running better now than it did a couple days ago, but I think it still needs some help. I'll most likely throw a can of Sea Foam into the gas and see how that does for now. I also need to double check the jets to make sure those are still set properly. It ran pretty well last year, finally, but this year it's giving me fits.

My problem that I'm having a difficult time sorting out right now is that it leaks gas. I'm pretty sure the float is set properly, but it's possible it's off a bit. But it appears that the primer bulb is the issue, because if I disconnect the tube from the carb, it stops leaking. Does anyone have any idea what could be causing this?

 

It's the float in the carburetor not seating or it's sticking.
Find a place that sells nonethanol fuel or at least add an additive made to counter act the effects of it will go a long way to stop fuel related problems.
Any marina near by will have it or ask your local power equipment dealer where to get it.

 

There is a very small vent hole in the side of the carb that is blocked:

 

Very interesting. I'll have to take a look. Thanks!

 

There's no way it a "vent" leaking.

 

I didn't say that the vent was leaking I said that it was blocked, pluged up, not venting.
It is the atmospheric vent.

And if the atmospheric vent is blocked the carb will leak because:

Before the fuel is turned on the carburetor bowl is full of air. If the atmospheric vent is blocked the trapped air has no where to go. When the fuel is turned on it doesn't take much fuel to cover the fuel transfer port on the bottom of the emulsion tube post. As more fuel enters the bowl the volume of the trapped air prevents the level of the fuel from rising high enough to raise the float enough to close the needle valve. The fuel keeps entering the bowl. The air can't escape but the fuel can it is forced up the emulsion tube into the throat of the carburetor.