Diesel fuel ‘bugs’ are a range of bacteria and fungi generally known as hydrocarbon utilising micro-organisms.

They can metabolise or breakdown hydrocarbons – in essence ‘feed’ on the fuel.

Vehicles with poorly maintained fuel systems or tanks that are subject to water contamination (from water leaks, condensation, or contaminated fuel), or those that see infrequent use are most susceptible.

Fuel in storage can also become infested. These microbes mostly live at the interface between the fuel and water layers.

They can enter through tank vents or during fuel transportation and under the right conditions, some varieties can double their numbers every 20 minutes.

They often produce thick slimy mats of sludge that can block fuel systems and filters.

The acids they produce can also cause corrosion of metal and rubber fuel system components.

That or persistent fuel system blockages are obvious warning signs of possible infestation.

Treatment of infested systems includes draining and steam-cleaning of the tank, filter changes, and addition of a fuel system biocide to the fresh fuel to prevent reinfestation.

Ongoing system blockages due to dead cell material and potential reinfestation can result from biocide use alone.

Recurring problems are likely if fuel system maintenance, sources of water contamination and poor fuel storage practices aren’t also addressed.