Two-dimensional images of fuel distributions have been recorded in the intake of a fired 6-cylinder-4-valve spark ignition engine. As markers for the fuel a new exciplex-seed combination of triethylamine (TEA) and benzene was developed. Mixture formation and fuel evaporation of two different types of fuel injectors were compared inside the intake. The images were coupled with measurements of unburnt hydrocarbons (UHC) emissions of the two injectors in the exhaust gas. The behaviour of the fuel vapour distribution was examined at different times during the engine cycle. Instantaneous and averaged fuel distributions are shown and discussed in their influence on mixture formation.