I too have gasoline/Petrol fumes in my trunk/boot.
My tank is welded stainless steel with a 6" x 10" Oval bulkhead Fill Plate. There is a rubber...Neoprean? gasket between the plate and tank. The bolts are 1/4" NF stainless steel with Loctite gasoline compatible thread sealer. Each bolt has a stainless steel flat washer with bonded Neoprene sealing washers under the head.
Sender unit has a cork gasket with stainless 10-32 screws, thread sealer and stainless/neoprene sealing washers.
All bulkhead fittings and hose fittings are sealed where called for. Vent hose is not connected in this photo but is connected and vented to the outside of the trunk body into the wheel arch.
The only thing I did not do was to apply a gasket sealing paste/compound to the oval rubber gasket between the 6" x 10" bulkhead plate and tank. Could this be the area where fumes are escaping?
I have no leaks anywhere.
See photo of the installed tank below. Thanks!!!
http://www.clubcobra.com/forums/pict...pictureid=2782