Fuel droplets flowing in a carburetor venturi are analyzed by one-dimensional, steady, two-phase flow theories. Fuel evaporation and transportation are computed in terms of percent evaporation and droplet velocity, respectively. Among important parameters affecting droplet evaporation are droplet size, droplet temperature, and air temperature. Less significant parameters are air velocity and air pressure and air-fuel ratio. The mathematical model can be used to evaluate order-of-magnitude effects of various design parameters affecting fuel evaporation and droplet transportation in the carburetor and induction system of an automotive engine.