Franklin, Donalex mentions Fuel Set, This product was developed in Perth western Australia and I was the importer to New Zealand in the 90s. It is a great non toxic product and I still use it to keep my fuel clean. Your problem may be something to do with "bug" as this often causes blockages. With biocidal treatments sometimes the blockages get worse after treament as all the dead bug comes through at once. Fuelset seems to clear it with less blockages post treatment. What is less known, however, is what the bug does to your fuel. Basically it lives at the fuel\water interface and feeds on sulphur in the fuel. It gives of hydrogen sulphide gas and acid compounds, creating acid conditions in the fuel. The acid ofcourse gets straight through the filters and can damage your hp pump. The Fuel Set has the effect of retarding this process and neutralising the acid. If I was you i would be dealing with the bug problem with some urgency. Treatment ratios used to be 1:4000 for normal usage, and 1:2000 for contaminated fuel. Greater does rates than this don't achieve anything other than damaging your wallet. So you can see you won't need much to fix the problem. Good luck.