Small Engines (Lawn Mowers, etc.): Problem with Craftsman/Tecumseh engine, engine 143, tecumseh engine

Question
Craftsman engine #143.414292, equivalent Tecumseh# TVS105-53153H.  Engine starts then stops seconds later. From the reading I've done I've been pointed to a fuel problem, but 1) the fuel is new and clean, 2) there does not seem to  be a fuel filter anywhere on the engine, 3) when I disconnect the fuel line from the carburetor it flows freely from the hose, 4) the spark plug is new and gapped correctly and it has a gasoline odor on it, and 5) I've completely disassembled and cleaned the carburetor.  

I'm at my wits end since I can't get the engine to start and remain running, and can't imagine what else it could be since I believe I've ruled out a spark problem and a fuel problem.  Any ideas?  Thanks for your help.


Answer
I don't think you've ruled out a carburetor problem.  If the screw that holds the bowl on has a couple of holes in the side and one in the end then it's the main jet.  The holes in it must be clean or the engine will do what you describe.

If they're clean and you're satisfied that the carburetor has been cleaned as best as you can, then I think you'll need to replace it.  We use ultra-sonic cleaning but still replace most of these carburetors.  What happens is that a little corrosion or something clogs up the small circuits in the carb and you just can't get them clean.  Thanks, PK.