Fuel tank pressure and fuel coming out of trumpet breather 1.8GTI Tintop

I took my Golf out today for a short run which included sitting in some slow traffic for about 15 minutes. I started to notice the odd whiff of fuel when I was through the traffic jam, when I got home I noticed drops of fluid on the drive and when I looked under the car I could see that some fuel had leaked out of the trumpet breather. I removed the fuel cap and got a massive whoosh of air coming out of the tank including a splash of fuel. I have always had the rush of air when I've removed the fuel cap but thought this was normal. I've read a few posts about the rush of air and it's a bit inconclusive whether it should do it or not! I wasn't too bothered about that but obviously the fuel leaking from the trumpet is is quite worrying. Used the car again this afternoon and did about 15 miles and no fuel smell or leaking from breather. Can anyone shed any light on this? The car has a new VW Heritage tank fitted about a year ago along with new filler neck, rubber filler neck hose, fuel pump and a various components on the fuel system. The gravity valve is original and I never even check it's operation when everything was in pieces (I never gave it any thought). The tank doesn't have the baffle plate in the filler pipe like an original tank would have. I have done about 1500 miles since fitting the tank last year and has never done this before.

I can't help as such, but my carbed 1.1 gushed at me and actually spat fuel at me yesterday too.

I recently replaced the fuel cap with what VW Heritage claim as a vented cap….. That was my issue, pretty sure the cap isnt venting.

This one

https://www.vwheritage.com/171201551l-fuel-cap-vented-locking-in-black-mk1-golf-scirocco-1978

I've put the ugly old cap that the car came with back on and that solved my problems.. No more gushing, also the car now starts and runs better without the heritage cap on.  

Thanks for the reply. It's quite a lot of pressure that builds up in the tank and I'm not sure where it comes from! I might have to remove the gravity valve and test it. Given that mine say in a garage for 7 years with water in the fuel tank I suppose it's likely that that is knackered along with the fuel cap!


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