Fuel filling problem

[samk]

I have a recurring problem with my fuel filler neck that my mechanic cant get to the bottom of. He fitted a new tank ( probably a late style one) to my 83 Aircooled. Ever since fuel gushes back out of the filler hole when filling up unless the bear minimum pressure is applied to the filling hose.

My initial question is how was the system designed to allow the air to disperse when the fuel is added? is it though the breather system or via the filler neck?

I know some of you have posted on this query before but I'm trying to get the bottom of it again after another unsuccessful visit to the mechanic. he is willing to sort it for me but i'm trying to get to the bottom of possible causes before I go back to him.

thanks,

Sam

[CovKid]

Blocked pipes to expansion bottles under front arches. These are what allow fuel to enter without it spitting back at you.

[simple]

If he replaced the tank I assume he replaced all the breather hose to those 2 tanks, on mine there is some small copper solid pipes that go between top of tank and expansion tanks. I presume this is solid as it sits over chassis and therefor might rub if it was rubber hose. When removed the tank and all this stuff last weekend I found these pipes blocked. This may explain your problem, even if you put new hose on the expansion tanks you may have a blockage in these small pipes.

[samk]

thanks covkid and simple -i'll suggest these as things to look at when i take it back to the mechanic