Small Engines (Lawn Mowers, etc.): Gas comes out of primer bulb, vent hole, air mixture

Question
Thank you VERY much for your response. Today I put in a new spark plug gaped at .030. The snow thrower is six years old. It still starts very easy but runs rough with the choke opened completely at high speed and runs smooth at idle. The choke has three positions, closed, half open, and full open, it runs the smoothest if I keep it at half open while at high speed. There are no adjustments for air mixture on the carburetor that I can see. Also, the gas no longer comes out of the primer button.


Phil

-------------------------
Followup To
Question -
On my Craftsman 5 hp 22in snow thrower - Model 536.886141. At the end of every winter I always change the oil and drain the gas. Today I filled the tank with gas and a stream of gas came out the vent hole of the primer buttom (this has never happened before). I pushed the primer several times to try and get the leak to stop and could'nt so I started the engine and the leak finally quit. Now with it warmed up and the choke open the engine run rough at full speed but smoothly at idle. Is the primer button bad or what do you think is wrong, it starts easy every time. I am also concerned about safety, if this should start leaking again when I'm not around, so for now I moved it out of the garage.

Thanks for your help
Answer -
Hi Phil,

The leak was probably caused by a sticky carb float, that didn't close.  If the leak has stopped, then the float is most likely working again and not a safety issue.  
The rough running is probably due to another carb related problem.  I suspect that the cause to all this a bit of old gummed fuel left, after you did the draining.  I like to keep the fuel system wet with fuel and the only way to do this is by stabilizing the fuel in the tank and running the engine for a few minutes to get it into the carb.  Try the engine again and if the roughness still continues, let me know.

Best,
Michael

Answer
Hi Phil,

The engine running well, only on 1/2 choke, indicates a lack of fuel flow, which again points to a blockage in the carb.  Check again for carb mixture screws but some models don't have them.
If it doesn't improve, you will need to remove the carb, disassemble it, clean all the small internal openings and blow it out with compressed air.  Probe each and every hole with a small wire.  Adding a carb rebuild kit wouldn't hurt either.

Good Luck,
Michael