I have a John Deere GX 345 with a FD611v engine. Its blowing smoke from the exhaust mixed with the strong odor of gas. I checked the oil and it has been thinned down with gas. Drained and replaced with new oil and filter. The motor will not run good at idle and you have to run full throttle and runs fairly smooth until it starts smoking (have to play with the choke a little on the throttle up). Pulling a load such as engaging the blade of course causes it to smoke worse. I pulled both plugs and they don稚 look too bad (little carbon no chunks of gunk) is it a carburetor issue ( stuck float observed some dirt in the gas tank) or are the valves burned out? It痴 a freebe just trying to figure if it痴 worth saving