Ultra Low Sulfur Fuels and Microbes
When the EPA mandated the reduction in sulfur for off-road engines by 97%, it created a cleaner fuel, but it created a problem too. The current changes in fuel composition (from 500ppm of sulfur to 15ppm) may directly affect microbial growth in diesel fuel used in generator sets. The lower sulfur fuel is more vulnerable to microbial growth. When microbes consume fuel they leave behind by-products of sludge and acids. The acids can cause corrosion on wetted metallic surfaces above the level of the fuel and sludge can clog filters.
To limit microbial contamination we recommend that you keep diesel fuel tanks free of water and incorporate a desiccant dryer on the vent pipe. Water should be checked on a regular basis and removed if greater than 1 inch. Establishing a maintenance program that includes testing and treatment will help you prevent bacteria, fungi and sediment buildup that can clog fuel lines and injectors. Generator manufacturers recommend fuel polishing to be part of a regular maintenance plan for sets with long idle periods. Ultra-low sulfur diesel presents some new obstacles, however, implementing a fuel system maintenance program will improve the performance of backup and emergency power generators.