Follow shaka's advice to clean the screen, and DO NOT use Chem Dip for this. It will destroy the diaphragm. Once you clean it just test it for flow. Glad to here you found your main trouble. I assume by upside down you mean 180 degrees turned? I also use an inline fuel filter from Ace Hardware. $1.25 each, and I relpace it about once a month. W/ your scoot sitting there is most certianly junk (rust) in there. I have used Hydrocloric acid to clean rusted tanks w/ good results. You can get a gallon for about 5 bucks at any good hardware store. It is usually sold as brick wash. If you deceide to try it be carefull. 1 minute will burn the rust 2 will burn the tank!