Interestingly, no perished hoses, no sign of any leaks, so no idea.
The rubber on the fuel cap had dried out and hardened a bit, so replaced it and seems to have cut the smell, so here's hoping.
Really need to spend some more time on the car this coming year.
Only done about 20 miles in it this year and feel really guilty for it just standing there, been restoring the Alfa this year which has taken up a lot of time, so hope to get that finished off, sell the T-Bird, then I can focus on the poor GTA.
I know it's a recurring theme around these 'ere parts that GTA's rebel if they aren't used enough.