Fuel leaking from filler cap

[iMacThere4iAm]

Here's a strange problem. Felicia had been consuming too much fuel and smelling petroley which I put down to an over-rich mixture, but today I noticed a drop of fresh petrol on the paintwork below the filler cap. This was not after filling up but simply after driving a short distance from home. Any idea what could cause petrol to apparently flow up the filler neck and leak out through the cap?

 

[Geoff in the Gully]

When I park my Lucy facing uphill at home with more than half full tank, on a hot day fuel in pushed up the filler pipe and flows out.
I think the fuel covers the inlet into the tank and the hot day expands the vapour in the tank pushing the fuel up the inlet.

 

[iMacThere4iAm]

Might be a blockage in the breather pipe which runs from the level gauge sender on the top of the tank to just below the filler cap, and is supposed to prevent that from happening. My problem could be related but I can't really understand it.

 

[Geoff in the Gully]

That's a thought, I'll have to check it out.

 

[malcolm]

I had a fuel smell in the R5 which was cured by tightening up one of the jubilee clips on the rubber tube between filler and tank. Spotted that by having a look underneath for leaks. Though to be fair that look was prompted by a steady drip on the garage forecourt after filling up.

The fuel seems to slosh up the filler in these cars quite easily even on a gentle drive. Might also be the fuel cap rubber seal or a problem with the fuel cap venting.