Ok to rule everything else out (carb problem) just take the dang carb off and spray a squirt of starter fluid in the intake hole. It should start within 1-3 pulls, then rev high, then die. If it doesnt start when you are doing that, its guaranteed not a carb issue.
I had a little tecumseh 5 hp fun power engine. worked on it for a while got it running, and was selling it. The guy wanted to see it run, and I coudlnt get it to start for the life of me. Turns out there was a green wire that had been tied into a kill switch, that had to be grounded to the engine so it would start. WTF, but as soon as I touched it to the engine it started right up. Dumbest thing ever.