Took the Dart to the local car show last weekend, I didn't "enter" as I couldn't make it for the morning and didn't fancy spending $20 to register, when I can park in the car park for for free. Got down there no problem, but then realised I hadn't got my phone, the battery on the camera was dead and the car smelled of gas. Spent about an hour walking round the cars then left. 20 mins after getting home I noticed a small puddle under the gas tank.
Further investigation was immediate and it turned out it was leaking from the repair I'd effected back in November. After much messing about with syphons (tip: cheap ones don't work) and electric fuel pumps I managed to drain the tank below the leak. Ordered a new one from RockAuto. CR11B is the one needed and they had one in stock for $170.
New tank arrived Friday and fitted it Monday. Nothing too difficult but the lesson of the day is fix it right first time then you won't have to fix it again.