Diamond Diesel Fuel Polishing

Preventative Maintenance - Residential

Emergency Backup Generators

Assure generator availability when needed. Reliable backup generator service is too important to leave to chance.

Diesel fuel can easily become contaminated with microorganisms such as bacteria, mold, fungi and algae. Water in diesel fuel will culture a microorganism or bacteria that feeds on the hydrocarbons in the fuel, therefore degrading the fuel.  Water is the worst form of fuel contamination. Good fuel is clear and bright. Diesel that has turned dark, almost black in in a far advanced state of degradation. This darkening is accompanied by a form of contamination that clogs filters and causes poor combustion.

Running the generator once a month until it reaches operating temperature, about 30 minutes, is not sufficient to reach meaningful filtration. Warm diesel returning to the tank encourages condensation and provides a ripe environment for microbial contamination.

Normal generator service provides for the changing of filters with an oil change, about twice per year and short test runs to verify the mechanical is working properly.

The generator test run time is insufficient for contamination to build up on the filter revealing a diesel fuel contamination problem.

Biocides may be added to the fuel to kill microbial activity, but this only causes solids and debris to settle to the bottom of the tank forming a thick sludge.


Symptoms of fuel problems:

  • Fuel over 1 year old
  • Loss of power or rpm’s
  • Excessive smoke
  • Transom soot
  • Clogged filters
  • Dark or hazy fuel
  • Particles or algae visible in the water separator bowl.

Once power goes out and the generator operates under full load, fuel circulates and clogs filters causing a mechanical shut-down due to fuel starvation. Continual filter changes address the problem, but do nothing to correct the problem.

Contaminated fuel should be replaced with fresh fuel or polished to a clean dry state.


It is more cost effective and environmentally friendly to clean the fuel.