Hi, we have recently sampled the fuel tanks on a complete mine site and the results indicated there were 25 % of the machines with biological growths in the tanks, these growths require water to survive so we found that;
Tanks breather were not being replaced, replace tank breather every service.
Water checks were not performed, Drain water off every service and if found check for water weekly.
We found that fuel filters were serviced but with the presence of water and machine heat if the tanks breathers were not serviced there was enough organic debris gaining access to start new growths,
Regards
Rob S
www.rttech.com.au