Small Engines (Lawn Mowers, etc.): Lawn mower wont start, float bowl, hp engine

Question
I have a tecumseh 6 hp engine in my lawn mower.  The mower is about 4 years old from Sears.  I drained and replaced the oil, put in fresh gas, changed spark plug and air filter.  Still won't start.  I removed the air filter sprayed carb cleaner into the carb.  It gave a 1/2 chug and puff of smoke like it was about to start, then no go.
What next can I do.  Note it was left with gas in it over the winter, a no no I believe.

Answer
Drain all the gas from the fuel tank.  Get a rag or container...to catch fuel.  Remove the carbuertor float bowl nut located on the bottom of the carburetor.  This will drain all the fuel out of the carburetor, hence the rag or container.

You should see some holes in the float bowl nut.  Clean as necessary.  Carefully install the float bowl nut, it is made of brass, soft and can strip easyly.

Re-fill with fuel and try to start.
Let me know what happens.
Eric