Frank, I'm not sure if you remember my horror story a while ago about my tank imploding. See the pics here:
http://www.kapital-sales.co.uk/desmo/images/Tank/ And read about it here -
http://217.199.188.40/control/boards...d.php?tid=3795 Final conclusion was that it was caused by bad venting of the fuel tank and quite possibly a defective vacuum pump.
I hope the same thing isn't just about to happen to you too!!
Phill