Engine hunting and surging. Poor or no starting. Running solely on choke. These symptoms often point to the carburetor. When a carburetor is clean and working correctly, the engine should start easily, idle smoothly, accelerate without stumbling, and run with normal fuel economy.
Carburetors can be expensive to replace. But this important part often requires TLC rather than an entire replacement. With a few tools, a shop towel, and a couple of hours, you can clean the carburetor yourself and save time and money.
The number of problems with carburetors has increased with the introduction of treated fuels such as E10, which contains ethanol. Ethanol, which is pure alcohol, attracts moisture and leads to corrosion inside the fuel tank and carburetor. Also, if E10 is left inside a small engine for too long, the volatile ingredients will eventually evaporate, leaving a thick, sticky, varnish-like product. This gummy varnish then lines the carburetor bowl and begins clogging up the small jets and ports, creating problems.
Even expired gas (sitting more than 30 days) poured in from a can might be dirty or contain rust that clogs lines. The solution is to drain old fuel from the float bowl and clean with carburetor cleaner.