Ethanol acts as a solvent in older engines and can dissolve old gum and varnish deposits from the gas tank and fuel lines. These deposits can then clog the very small orifices in the carburetor. ... They grab oxygen that's in the gasoline, preventing it from turning into gum and varnish.

Is ethanol bad for a carburetor?

Ethanol blends can corrode your carburetor, fuel tank, and other fuel system components and damage engine seals and O-rings, according to industry experts. And that means costly repairs at the very least–and engine damage at worst.

How do I protect my carburetor from ethanol?

Use a water separator filter in the fuel line leading to the carburetor. Since water collects in the filter, you can easily remove it. Change out any O-rings in the fuel system to ethanol compatible rings. A carburetor fogging solution prevents condensation from filling fuel bowls.