Help, petrol in filler cap housing

[vinvan]

Can anyone help, went for a short run in the bus today started to smell petrol, on investigation we have petrol pooling in the filler cap housing looks like its coming up from the bottom vent hole (see Photo).
When fitting, the tank was clean and all rubber vent connectors and the rubber filler pipe were new
is it possible that the filler cap is to tight thus creating a vacuum in the tank and the fuel is escaping through the vent hole? but just guessing
PS. The tank was half full
any help would be appreciated
Thanks Vinvan

 

[sparkywig]

I've got the same problem, it's escaping through my filler cap during driving.
I've changed the gasket and cap a couple of times but still have the issue. I'm going to remove the filler neck and compare it with a couple of others to see if it's worn/damaged.

 

[vinvan]

Thanks Sparky