Briggs and Stratton problems?

i have a 5 hp, 2000-2002 (im not completely sure) briggs and stratton engine on my go kart. I was out driving it one day when it died. i figured it overheated, so i let it sit for a half hour before coming back. when i came back it would idle fine but as soon as i pressed the gas it would die out. I cleaned the spark plug and the air filter, still didn't work. so i replace the carburetor diaphragm, now it wouldn't even start. i put the new and the old diaphragm on it, and it runs in choke, but when i press the gas OR move the lever to run it dies out like its not getting fuel. so i check the spark plug, it sparks great. i poured a bit of gas in the chamber, and it runs for about 3 seconds before dieing out. i spray carb cleaner in the carb, still nothing. the only thing left i know of to do is drain and clean the tank, but that would take hours since there are at least 3 things (including the throttle cable) to unhook