16 Tips for Generator Operators to Improve Diesel Fuel Quality

by Contributor oltwodogs ‎08-26-2010 08:32 AM - edited ‎08-26-2010 08:35 AM


Contaminants can decrease your engine's efficiency, increase your costs, accelerate wear and eventually, cause expensive repairs. So what should you do to keep your fuel as clean as possible? Here are three common culprits of dirty fuel and a few simple recommendations that may save you money down the road.

Sediment: it decreases the amount of usable energy in the fuel. How do you get rid of it and how can you prevent it from entering the fuel tank?

1. The most cost effective method to remove sediment is to let it settle in the bottom of the tank and drain it.

2. Most sediment will be caught in the fuel filter, but excessive amounts will require that you change the filter more often.

3. To decrease the amount of dirt entering the fuel tank, add an air filter to the fuel tank breathers.

Water: it can condense in fuel storage tank, becoming a subsequent source of corrosion and a breeding ground for microorganisms. Here's how you can reduce the level of water in your fuel:

4. Drain the fuel tank regularly.

5. Buy fuel from reliable sources and monitor the quality frequently.

6. Use water separators.

Speaking of Microorganisms... bacteria, fungi, and other microorganisms grow where water and fuel meet. How can you get rid of them?

7. Use a biocide to kill microorganisms when the tank is full so any growth on the inner side of the tank will be eliminated.

8. Filter the fuel after using the biocide to avoid plugging engine fuel filters with dead microorganisms.

Here are a few more miscellaneous tips:

9. Clean dirt, dust and other debris from the engine compartments before removing the fuel filter and other fuel system components for maintenance and repairs.

10. Any time your fuel system is open, contaminants can enter the system. Tightly cap or plug all openings during repairs even if they are needed only for a few minutes.

11. When working in especially dusty sites (construction, mining, etc.) airborne contaminants can be drawn into engine fuel tanks through the vent tube. Likewise, a vent in the fuel tank cap can ingest dust. Be sure vents are properly sealed. Contaminants can also develop during storage or enter the system through improper fuel transfer.

12. Clean reusable parts with solvents using proper cleaning and drying methods.

13. Never place components directly on the ground.

14. Don't reuse seals, replace them.

15. Perform routine inspection of fuel line connections from the tank to the fuel pump.

16. Test your fuel regularly to ensure it's of the best quality.

So... I'd like to know:

  • Do you have any tips you've used successfully?
  • How old are your fuel storage tanks? Do you have them inspected?
  • Are you testing your fuel from your vendor before and after entering your fuel storage tanks?
  • Have you switched over to Ultra Low Sulfur Diesel (ULSD) Fuel? If so, did you clean you fuel storage tanks prior to switching?
  • Are you changing your filters more often than recommended? If so, have you considered the causes?

by Super Contributor
on ‎08-26-2010 11:56 PM

How about instead of sealing tank vents, which you should never do, install a combination particle and dessicant filter, use the ones made for hydraulic tanks, have done this on several sites with large ambient changes and lots of dust, made a noticable difference.


Add biocides when you buy fuel, actual usage and dose rates depend on your location, if you're in a dry clean climate and roll your fuel rapidly, then adding biocides may have litle impact.  If you store fuel longer than 3 months, are in an area where you have rapid temperature changes, use ULSD, or in humid or coastal areas, use biocide everytime you buy fuel.  For longer term storage consider fuel sampling and fuel polishing.  Prevention is key, waiting until you have a problem is way mor costly than preventing one. Also consider fuel stabilizers for longer term storage, just make sure to get from reputable suppliers.


Primary filters should always be installed with restriction gauges, what a dumb way to save a few bucks, finding out your primary filter is plugged when the engine bogs down, amazing how many times it happens. Better yet a pressure switch and alarm or indicator, since hardly anyone anymore walks around a running standby generator, especially during weekly runs.


When we made the change to ULSD in California several years ago we recommended to many of our customers to buy on road fuel the first time around, then use it in their fleets and equipment to roll it over more quickly, a lower cost way to "flush" a tank when it's hard to justify otherwise.

by Visitor Allentp
on ‎09-01-2010 09:57 AM

Should the ZINC issue be mentioned? Any repairs, modifications, or updates to the diesel fuel system must not include any zinc materials (like galvanized fittings, or caps made from a material containing zinc, etc.) Even a very small amount of zinc can contaminate a diesel fuel supply and may cause very expensive engine repairs. Make sure there are no galvanized hose or line parts used when cleaning out the tank. 

by Contributor wlj1943
on ‎09-01-2010 02:02 PM

Good job Kevin. I have some possible additions.


1. Re moisture, my marine experience adds one important item, mostly applicable to standby gensets: Keep the tank as full as possible at all times. This reduces condensation to near zero, as there is little volume of air in the tank. Also , keep fuel fill piping tightly sealed and full of fuel if applicable and possible.

2. Good tank design incorporate a sump and shape to collect moisture and crud and funnel it there. The key is the sump needs to be drained at regular intervals. I have seen many packaged sets (some even done by Cat dealers) that do not have this essential feature.

3. Mike's combination filters suggestion for vents works great in our experience, but must be maintained. Some brands of dessicant filters or the housings have a color changing sensor that makes this a lot easier.

4. Great Filters and water seperators are a must. I have never seen an installation that had too many.

5. For zinc issue, I think some further engineering advice from Cat is needed; is there a tech paper that is current? 


on ‎09-03-2010 08:58 AM

We are currently polishing the fuel in the fuel tanks then I follow up with the customer on adding a permanently installed fuel polishing system to the fuel tank. We have had great success with this. It is amazing to me that no one thinks about the quality of the fuel that they have, most customers realize the importance of maintaining their equipment and being proactive, hardly anyone thinks about the fuel that have onsite. In the stand by power world, that fuel may be as old as 5 years! The industry standard is to polish the fuel at least once per year and to have your fuel analyzed by a reputable lab once per year.


We have had a lot of success with Algae-X systems. We currently have 8 portable units at our dealership that we use to polish fuel for our customers. It is a real eye opener when one of our technicians pulls a sample from the customers fuel tank, puts it in a mason jar, and they see what is actually in their fuel. The Algae-X fuel polishers filter the fuel down to 3 micron, not only does the machine remove the water and sediment from the bottom of the tank but it removed all the emulsified water and microbes floating around in the fuel itself.


When the new tier 4 engines come out, any sort of contaminants in the fuel will cause an engine failure, just some food for thought.

on ‎09-17-2010 03:12 PM

Good article Kevin, I think as time passes and as customers are refilling there fuel tanks with ULSD, the need for better maintenance practices of long term stored diesel fuel will become even more important.  Diesel fuel for most standby generators at this time is probably a mixture of Low Sulphur Diesel and Ultra Low Sulfur Diesel fuel.  


As the diesel fuel in these units becomes a higher percentage of ULSD, cold weather problems should become more apparent. ULSD can hold twice as much water in suspension as LSD. The lower the temperature the less water the ULSD can hold in suspension.  At 30⁰F ULSD can only hold about 35% of the water it can at 75⁰F. When the fuel temperature decreases the water falls out of suspension and appears as tiny droplets of water. When the temperature falls below 32⁰F these water droplets become ice crystals and will plug fuel filters. Many times these ice crystals will be mistaken for wax.


Wax dropout is another problem that occurs with ULSD. It appears that wax dropout occurs when fuel temperature remains between 12⁰F and 0⁰F for a period of time. This causes the wax crystals to accumulate in the bottom of the tank. It also requires a much higher fuel temperature to reabsorb this wax dropout back into the fuel.


In the past a blend of #2 Diesel fuel and Kerosene was the remedy for cold weather operations. Now first of all you are not allowed to mix Low Sulfur (≥15PPM) Kerosene with ULSD.  ULSD #1 is available but can sometimes be hard to find. To further complicate matters mixing ULSD #1 does not lower CFPP as much as it did with LSD. Previously it was thought that by adding 10% Kerosene to LSD#2 you would lower the CFPP by 5⁰F. That same mixture of ULSD#2 and ULSD #1 will only lower CFPP by 2⁰F. If you decide to use an Anti-Gel additive make sure that it is rated for ULSD. The older Anti-Gel additives appear to be ineffective on ULSD.


Going forward to effectively treat ULSD and prevent fuel problems in standby emergency generators will take much more attention than what was required in the past. The importance of providing our customer with fuel testing, additives and fuel polishing services will increase dramatically as ULSD phases out low sulfur diesel in standby generator sets.



by Industrial generator service florida
on ‎07-28-2015 02:10 AM

Fuel Testing will detect any fuel deterioration before it becomes an issue Fuel polishing removes any sediment from the fuel tank, filters contaminants and strains any water. All fuel is recycled with no fuel loss and  Fuel Treatment. Ensures that the fuel is up to par and ready to perform. Additives fight micro-organism growth, prevent gelling in cold temperatures, boost cetane levels and provide additional lubrication.

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