2011 Ford Flex. Gas is leaking when tank is max, but doesn't leak when sitting or when filling it less than full. What could cause this?

2011 Ford Flex. Gas is leaking when tank is max, but doesn't leak when sitting or when filling it less than full. What could cause this?

Sometimes the fuel vent line and vent in the fuel cap can get slightly clogged, might want to have that checked.

Offhand guess would be that the leak is in or near the Top - not the Bottom. Since that's also where the connections for pump and fuel line are you can hope that's where the leak is rather than a crack/hole.

A leak is caused by a leak.

Hole in gas tank