Small Engines (Lawn Mowers, etc.): Engine Diseling or surging cannot run without chock at least part way, float bowl, fuel jet

Question
I have a new MTD Snowthrower purchased last year, 8hp. with a 4 cycle tecumseh engine model # LH318SA. Engine will only run 1/2 chock or full chock and surges when running, no black smoke. I think carberator needs adjusting. Manual does not have info on adjusting carb. Would you adjust this carb the same as say on a riding tractor. Does not show where idel mixture screw is located or fuel run mixture screw is located. Cannot find any illustrations on net for these locations on carb.

Thank You;
Terry

Answer
Carbs are non-adjustable.  You can try draining the carburetor float bowl by removing the float bowl nut.  While the nut is off, blow compressed air through it with air from an air compressor.  The holes in the float bowl nut is the main fuel jet.

Let me know if draining the carb bowl helps.
Eric