There is no paint inside the tank. The tank was painted 2mm beyond the top point squeezed by the rubber seal. So 2mm of paint was inhaling fumes from inside the tank. My sense tells me that paint is not suppose to reach the rubber seal, A fuel resistant coating yes but not paint.
I used a flash light and a dentist mirror to verify there's no goo inside the tank. I think I'm set now ready to turn it to a descent painter.
The PO just told me that the one he took the tank to was painting...Tractors
Good to know that he at least plugged the hole. On the top of the rim, where the seal meets the tank, there is "usually" a slightly raised section of metal that is stamped into the filler neck. Paint should never be applied to the top / flat portion of the filler neck as has been made clear. I always spend a few minutes to sand the top to the filler neck with some 400 to ensure that nothing remains but clean metal, then treat it with a few drops of air tool oil, rubbed in with a finger.
