fuel tank leaks when full. pressure build up?

i took my defender to the petrol station and filled it up today, after a short drive home and getting out of the car i noticed a lot of diesel dripping out from under the tank, seems to be were the filler neck meets the tank. i opened the cap and was I instantly covered in diesel, but once i opened the cap the leak stopped. its been making a psst sound and theres been air pressure when i take the cap off for a while.

My thoughts are that pressure is building up in the tank cos the cap is blocked and this pressure is forcing the petrol out anywhere it can.

This is the first time in a long time its been full, normally i keep it half full.

would a new cap stop this before i go and shell out for one tomorrow?

dont fill it up:hysterically_laughi

check the breather tube isnt blocked failing the i would say its the cap.

Breather most likely, however get it sorted asap as I'm sure you are leaving a trail of crashed motorbikes and wreckage in your wake

Ghost said:

Breather most likely, however get it sorted asap as I'm sure you are leaving a trail of crashed motorbikes and wreckage in your wake

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BONUS!:hysterically_laughi

got a new fuel cap and fitted a new jubilee clip on the filler neck. all is good now!

if there is pressure in the tank this could be down to a damaged diaphram in the fuel pump. had this problem on a 1989 110 TD. in the end it damaged the seams on the tank. so i got the bill for a tank and the repare on the pump. diesel specalis will put a new daaphram or the other opion is a new punp which is not cheep.

i had a new fuel lift pump fitted today and it's sorted itself out, no pressure anymore. which is the main thing. i can go to asda tomorrow without fear of causing an RTA.