Small Engines (Lawn Mowers, etc.): B&S Quantum 120000, float bowl, new spark

Question
Worked to start the mower after a new spark plug, changed oil and new air filter installed.  Put in gas with fuel stabilizer.  Mower turns over and runs for 5-10 seconds and quits, pump bulb and it starts again. Tried to run with gas cap off if the vent was plugged still dies in 5-10 seconds or less.  Ran great last fall before winter

Answer
Classic dirty carb sympton.  Have you tried removing the float bowl nut on the bottom of the carburetor and draining the carburetor float bowl?  Make sure the hole(s)in the float blow nut are clean.

Let me know if draining the carburetor helps.

Eric