Performance of carburettors for gaseous fuels is not always satisfactory. Major difficulties are related to air-to-fuel-ratio control and to homogeneity. In that context, four carburettors, each based on a different principle, have been investigated. A major conclusion is that an integrated system is required for proper air-to-fuel-ratio control. Additionally, for sufficient homogeneity an even initial distribution of fuel over the air stream, followed by turbulence-induced mixing in a special section, is necessary.