Walmart offers the Berryman 15-oz. B-12 Chemtool Carburetor/Fuel Treatment and Injector Cleaner for $2.24. Opt for in-store pickup to avoid the $5.99 shipping charge. That's tied with our mention from a week ago and the lowest price we could find by a buck. It's designed to dissolve gum, varnish, and other fuel residues.