I am guessing that you are talking about the lines that are for overflowing carb bowls. This normally happens when one of the floats is stuck in the down position letting fuel flow into the bowl unchecked. Usually this happens when you have a piece of something stuck in the needle of the float assembly.
Many times you can take a long screwdriver or socket extension and tap on the carbs while the motor is running and it will dislodge. If you can't get it to stop that way, you may have to pull the carbs and clean out whatever is stuck in there.