What he is telling you could be it. It also could be the float in the carb could be stuck to causing that one carb to flood. If it was me and I was going to take that one carb off I would take all three off and at least clean them good. That way when I went back with them I would know that they didn't have trash in them. We do boat work at my dads and we do alot of carb work. Thats my opinion on it and if you have never done one I would get sumone who knows about them to help you if ur going to do it yourself.