14.5 briggs and stratten no start condition

I have a 14.5 hp Briggs and Stratten on my rider, i will not start, if i remove the air cleaner and put a bit of gas down it, it will run for a few seconds, then stall. I have had the carb off and cleaned it. If i remove the fuel line from the carb, there is fuel flowing from the line. Any suggestions please ?. thank you...