I got two answers back about my gas tank questions.  One says I should blow and rinse with gas, the other says that I should reverse the outlet with the return side, which is the most promising solution in my opinion.  
I would like to hear of many of you who went through this trouble to tell me what is the best to do and how to do it.  I will keep on asking about it until I get enough answers.  The chances are, this problem must be too common if I got two tanks plugged myself on one day.
Zoltan