Abstract: An anti-dieseling structure for demand carburetors wherein the air valve of a particular demand carburetor is provided with an exteriorly actuated lift lever, the same, when hand actuated, operates to lift the air valve. The tapered metering needle depending from the mechanically raised air valve is to make the fuel air mixture progressively more lean, with a carburetor operating at idle condition, to thereby starve the engine as to fuel intake and thus cause the engine to shut off in a positive manner and thus avoid dieseling. One or more carburetors may be accommodated by respective levers; where plural carburetors are employed, the levers are keyed to a common shaft that is rotated by control means leading to the dashboard at the driver's compartment. The engine, of course, will operate in the usual manner when the control cable coupled to the levers is not actuated, thereby leaving the air valves free to operate in the usual manner.