I had the same problem and followed all the advice. changed spark plug, emptied gas tank (twice) and filled with fresh fuel, took carburetor apart and poked holes with wire, put Seafoam in the gas and sprayed the the carburetor intake. Nothing worked; it would start with starter fluid but quickly sputter out. As another comment said, these walk mowers don't have fuel filters and I was told by Sears I would have to replace the gas tank. Since this was the only tip left and wasn't sure I had the skills I am officially giving up and taking it to the mower repair shop down the street. It's only a year old. The only other thing I can think of is that the mechanism that triggers the fuel release isn't working properly although it appears to be. but somehow fuel is not getting to the engine from the tank I think. If the shop can fix it, I'll comment back what it was.

Clean the Main Jet in the carb.

Hi TomPlum and thanks for the reply. I purchased it this afternoon and it should be delivered within the week. I know its Hondas cheap engine but the price was great and I noticed Toro, Husqvarna etc are using this engine as well so it couldn't be all that bad.

Ok, so i just got done replacing both head gaskets as they were both blown. Runs like a top now. I removed the deck and with the mower running i engaged the mower blades and it bogged the engine down and wanted to kill it. No sparks this time. Sparks might have been from the exhaust as one bolt wasn't tightened very well, or from the head itself as the gaskets had 2" spots missing. So i'm going to remove the clutch and clean it, one of the oil leaks dripped right into it and it flung allot of oil out when i started it last. It has to be something i did since it worked fine before i took it all apart, but not sure.