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8 Signs of Diesel Fuel Contamination by Microbes, Fungus and Bacteria

Mar 29 2011 - Posted by: Bell Performance

fuel contaminationDo you have reason to suspect you’re running on diesel or biodiesel contaminated by microbes, bacteria and fungus? Here are some signs to look for which can give you a pretty good idea:

  1. The need to replace fuel filters significantly more often than your baseline (microbes produce byproducts that clog filters)
  2. Frequent cleaning or replacement of fuel injectors (ditto)
  3. Premature wearing of rings and cylinder liners (microbes produce acidic byproducts that increase corrosion, as well as deposits that can produce wear in these areas)
  4. Excessive blow-by or an increase in oil consumption (these are caused by worn rings)
  5. Increase in fuel consumption (infested fuel does not burn as cleanly and will increase your fuel consumption rate)
  6. Fuel discoloration (infected fuel turns a dark khaki color instead of the bright yellow-green of fresh #2 diesel)
  7. Rotten fuel smell (sulfuric acidic byproducts from microbes give off a characteristic smell)
  8. Black exhaust smoke (caused by the engine’s inability to completely combust the infected fuel and the deposits and byproducts caused by the microbes)

Any and all of these symptoms can indicate a microbial infestation, whether in your own storage tank or the place where you get your fuel from. 


The best way to prevent microbial diesel fuel contamination is to control water buildup in tanks. Bell Performance Dee-Zol and DFS Plus are formulated to do this. But even the best housekeeping methods can fail sometimes, especially if not everyone in the supply chain is doing the same thing. Once you have a microbial problem, the only way to permanently end it is to kill it with a biocide like Bell Performance Bellicide.

Do you have any other experiences? Feel free to comment and let us know.

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