Originally Posted by cgaengineer
I have 5 of them...they all hang in our truck with tank above carb...all day, everyday...none of them do this. Before we had vertical rack they hung horizontally upside down...right side up...didn't do it then either. I'm willing to bet your problem is the heat from the sun in back I truck causing them to do this...it would cause the pressure in tank to increase.Posted via Mobile Device
This sounds like your answer.
Mine doesn't do it either. Try changing or cleaning the fuel cap vents.