When the seams fail it's usually along the top sides of the tank. It's easy to confirm. Fill tank. When home, remove rear parcel shelf and hold a kitchen paper towel along the edges. Dab it along and the leak will be revealed as the paper absorbs fumes and/or liquid and reveals a stain on paper. I spent many hours trying to cure it. Problem was that petrol attacks all the fillers etc. Including the ones that claim to be specifically petrol resistant. All repairs failed within a couple of tankfuls until...........I decided to replace tank and just ran gaffer tape over the seams to temporarily stop the smell. Complete cure, never troubled me again i the following 4 years.
Nick
