Fuel leak on a full tank

[james_16v]

Noticed a smell of fuel the last 2 times ive brimmed the tank after short journeys.
Had a look today under the car and there was a small patch of petrol under the tank that had dripped down the side.
Im not overly concerned as the smell goes away when the tank gets to about 3 quarters full.
Anybody know the likely problem?
Cheers

[Agreeable Slick]

Lift tank access point is probably leaking.

[james_16v]

Thanks for the suggestion.
Is there a seal or gasket around the lift pump that needs replacing that would cause this?

[Bjork]

Did you find the cause mate?

Mines doing same thing but can't find it.