My car has been running really bad on hills.(nose up) The revs just keep dropping until it stalls. (Stalls because its running richer and richer)

I parked it on a hill today with the air cleaner off and i could see a fair bit of fuel just dripping down onto the butterflies. Then when it stopped i could still hear fuel filling the float chamber. Also fuel then began to leak out onto the leaver next to the accelerator pump.

I'm going to look at it properly tommorow but has anyone got an idea of whats wrong.

Thanks