If what Fraser describes is the problem and the tank is in good condition, then Torque theres is a solution. 
Cut a large hole in the base of the tank around where the pipes exit and replace the damaged part of the pipe with a new piece either welded or brazed in place The biggest problem with carring out this repair is cleaning out the tank since petrol fumes are so highly explosive. I have seen this type of repair done by our local panel beater/spray painter on old bikes which are being restored and tanks are difficult to source. Whereas I have not seen it done on a fazer tank it would be a similiar procedure. Cutting the base usually prevents having to respray the full tank just the base where it would not be necessary to have the pain match perfect.
Blocking the hole as Fraser has done is certainly a workable solution abeit a short term one.
This is becoming more of a problem as the models age and any tank you buy could end up with the same problem. Bikes garaged or covered when idle as less prone to the problem.
Cut a large hole in the base of the tank around where the pipes exit and replace the damaged part of the pipe with a new piece either welded or brazed in place The biggest problem with carring out this repair is cleaning out the tank since petrol fumes are so highly explosive. I have seen this type of repair done by our local panel beater/spray painter on old bikes which are being restored and tanks are difficult to source. Whereas I have not seen it done on a fazer tank it would be a similiar procedure. Cutting the base usually prevents having to respray the full tank just the base where it would not be necessary to have the pain match perfect.
Blocking the hole as Fraser has done is certainly a workable solution abeit a short term one.
This is becoming more of a problem as the models age and any tank you buy could end up with the same problem. Bikes garaged or covered when idle as less prone to the problem.