c200 sport petrol tank

[bazfj40]

hiall,i have a question about the tank on my car, where the filler pipe comes out of the tank about two inches there is a square joint which i believe is probably plastic welded at manufacture but mine has what looks like fibreglass wrapped round the joint and when the car is running the fibreglass looks wet from petrol, if i take the petrol cap off it stops leaking at the joint, if i put the cap on again it starts leaking again and i also get a whoosh of air from the downpipe when taking the cap off, i know there is a metal flap at the bottom of the filler pipe so cant understand how petrol is getting up to this joint, is the tank under pressure when the cap is on and is this normal, i know there is a vent pipe on the tank so thought that would relieve any pressure in the tank, is another tank wanted and is there any problems in changing it. hope i have explained this problem ok, thanks baz.

 

[bigasotonuk]

Hi,
I may not exactly grasped this, but have looked at the vent pipes to see if they blocked?