Toro Ride-on Won't Start?

My Toro 17-38 axle worked fine til I ran out of fuel. I cleaned the dirty fuel tank and replaced the fuel filter. Per other comments, I turned the air vent on top of the motor counterclockwise 2.5 turns to see fuel sloshing in the air in take? On starting the air vent spins about .5 - 1 turn then stops with a clunk. Further start attempts just give a click sound, unless I turn the vent counerclockwise again. I would appreciate advice.