Seems that Exmark has recognized the problem of vapor lock. I was recently at the local Exmark dealer and several new units have the gas line wrapped in a "reflective/insulated" cover to protect it from the heat. Have a brother in law that had a similar problem with an old farm tractor and wrapped the gas line in aluminum foil which solved the problem for him. All that being said, if there is debris in your cooling fan housing you need to address that as it is affecting more than your vapor lock.