its called diesel bug its a microscopic organic life form espesialy prone to live in very low sulphure fuels like road diesel normaly it isent helpwd by the small amount ov water at the botom of ure fuel tank /also as ure fuel level drops air is drawn in this condenses as water and runs down the tank called TANK SWEATING . when the weathe warms up drain the tank totaly and preferbly steam it out at least flush it out thouroly then alough to dry out VERY compleatly , to prevent sweating keep the fuel level as full as posible -no moiste air = no sweating. think about adding a in line filter/seporator - try e bay. look for diesel filter. good luck.
lee jcb mecanic
March 2011