The tractor is a Cub cadet XT2 with Smart Choke (which sucks, by the way) and the bottom of tank is actually almost even with the top of the carburetor, but it has a fuel pump. Not sure why it isnt gravity fed? Anyhow, should gas actually run through the fuel pump when the mower isnt running, or do you think its got a bad diaphragm or check valve? I also get a gas smell when i smell the dipstick. Could the gas be going through diaphragm and into the valve cover where the pulse tube is and down in the oil? Any HELP would be appreciated..Thanks