Visited KGRE and KVLA this afternoon in my quest to hit every public airport in IL. Downwind at Greenville, ran my GUMPS: fuel left tank, gear down, mixture rich, fuel pump, lights, seatbelt. Short final.... maybe 300', the aiming point starts to rise in my windshield, so i added some power... no response.... realized the engine had quit. After about 5 minutes of shock, I decided I'd better do something as it was looking like clearing the threshold lights was about 50/50. Mixture is rich, let's see, it was running on the right tank, let's switch back....oh it's off.... how did that happen? Back to right tank....100'agl....VROOM! Whoa... right rudder! "Greenvile traffic, 35E going around.... Need to take a look at that stop.... and be more careful about flipping that little lever.