I just rebuilt two with the same problem..
I just rebuilt a couple of 95 skis.. Aftet fixing the pumps a motor and other assorted problems I found the carbs needed to be rebuilt.. One of them still had problems after I did the carbs.. It turned out to be the fuel selector valve was clogged even after cleaning it!! so I just eliminated it and it runs great... The help topics here are the best.. Made my life a lot easier,,,