Carburetor cleaning that actually works (the dunk-and-spray method fails)

Take it all the way apart: bowl, float, needle, main jet (it is often the bowl bolt, with tiny cross holes), pilot jet, the emulsion tube. Every brass piece out. Spray carb cleaner through every passage until it comes out the other side, then compressed air. The passages that matter most are the tiny ones you cannot see: the idle circuit and the holes in the main jet bolt. A single strand of copper wire from a lamp cord clears them.

New bowl gasket, float needle if the tip has a ring worn in it. Set float level per the manual (usually parallel to the body when inverted). Reassemble, fresh fuel, start.

If the carb is a $15 part online for your model (most Briggs, Honda GX clones, Tecumseh), buy the new one and keep the old as a spare. Your time is worth more.