I have a Skeeter zx22 w/ a 60 gal tank. The refueling port is Perko. When refueling it is obvious that fuel flows from the tank into the vent line thus restricting fuel flow into the tank. When I blow low pressure air into the vent line the restriction is cleared and air rushes out. I have to blow air into the vent line 2 or 3 times when adding 40+/- fuel. DIY suggestions will be appreciated. Thank you.