Lawnmower Engine Starting Tips??

[NoodleKnight]

Sounds like the A/F mixtures are somewhat fubar-ed.
I think the reasoning behind why the instructions (on the carb-cleaner bottle) say not to use while not running is because the stuff is pretty flammable -- if you cranked your engine right after you sprayed a bunch there's a chance something can go bad. Additionally, the engine has to suck the stuff in, also carb-cleaner has xylene, which smells bad, and is a carcinogen. Just get a pal to crank the engine continually while you spray inside the air intake.

All carbs make a hissing noise, it's part of their design to get the air flow moving around the intake... if it's pretty loud then I'd definetaly say there's stuff in your carburetor that's probably causing your engine to choke.