Does Your Filler Cap Look Like This?

Rusted filler cap diesel tank cap

Tank filler cap – initial rusting is an indication of the presence of microorganisms and possibly poor fuel quality. This tank was installed at the same time as a tank right next to it. One had rust and one did not. The variations could have been initial fuel quality, environmental conditions or other factors, which necessitate regular diesel fuel polishing.

If Yes…Your Generator Might Not Run When You Need It To.

Fuel-related issues are the most common causes of a back up generator not starting! Rust, tank corrosion and clogged filters, are common problems that are connected to fuel related issues in back up generators.

But what causes these problems?

Algae, yeast, bacteria, and fungi.

These problems might be present in your diesel fuel and reside inside your generators engine, without you even knowing it.

They can permanently damage your generator’s engine and make it unreliable, therefore allowing it to fail exactly when you need it most.


(left to right) Signs of internal diesel tank rusting; External and internal diesel tank rust; Tank conditions directly impact the quality of the fuel and thus the performance and lifespan of your generator engine

Because Of The Way Backup Generators Are Designed, It Creates The Perfect Scenario For Algae To Grow.

First, mandatory safety vents allow air in and out the tanks, in the Houston area our high percentage of humidity in the air adds moisture, and condensation to your fuel.

The area where water meets diesel is the perfect environment for organisms to grow, moist and dark.

And in a backup generator, fuel sits, undisturbed, allowing organisms grow. Creating particulates, sludge, and rust inside your tank.

Clogging filters, damaging your equipment, and increasing the chance that your backup generator won’t work when you need it to.

The Most Critical Factor In Whether Your Fuel Starts Growing Algae and Other Organisms is Fuel Quality.

The cleaner your fuel is, and the cleaner your fuel stays, the less likely your fuel develops organisms.

However, there are a number of factors that determine fuel quality…

  • Environment — hot summers and direct sunlight make your tanks expand and contract, introducing more condensation
  • Amount of fuel in the tank — a half-full tank has more air in it, and leaves more room for condensation to form inside the tank
  • Run time — running a generator more frequently disturbs organism growth
  • What’s already in the tank — sediment and debris settle and build up over time
  • How clean the fuel was when the tank was filled — fuel grade and quality when delivered is vital.

(actual diesel fuel samples from left to right: sludge; high water to fuel ratio; sludge; sludge, rust, particulates; particulates; few visible particulates but enough to clog the smaller fuel injectors on more modern generators; the far right sample has no visible particulates, but a lab report showed it had a severe presence of microorganisms. A visual inspection sometimes isn’t enough.

Unfortunately…Even Fresh Fuel Can Be Contaminated as Soon as it is Introduced To The Existing Fuel

Clogged filters and rust on the filler cap are usually the first visible signs that you’ve got these organisms in the tank. But even a quick glance at your fuel can tell you if something’s wrong.

All of these samples were taken from the middle of diesel tanks with various states of overgrowth.

Left alone, these organisms will continue to damage your tank, and you run the risk that your generator will shut down during an emergency — just when you need it to be up and running the most.

Polishing and Treating Your Diesel Fuel Removes Organisms, Kills Bacteria and Ensures Your Generator Will Work as Intended

Polishing filters your diesel fuel, removing living organisms and filtering out sludge and sediments that clog your filters, block injectors, and stop your generator from running as intended.

Not only does it maintain your tank and prevent corrosion, but regular fuel polishing also ensures that, in an emergency, your generator will run for more than a few minutes.

Regular fuel polishing and treatment is key to backup generator performance.

Under the right conditions, any fuel tank can develop organisms. Even one that was perfectly clean to begin with.

Regular fuel polishing is key to backup generator performance.

Under the right conditions, any fuel tank can develop organisms. Even one that was perfectly clean to begin with.

Cleaning Your Fuel at Least Once A Year is Critical to Making Sure Your Generator Operates as Needed, When Needed.

At WPP, our Diesel Fuel Polishing service is part of our preventative maintenance program. We strive to maintain and prolong the life of your generator. Plus, it gives you peace of mind knowing that your generator is in perfect working order, and can run for hours whenever you need it.

We start by taking a representative sample of your fuel, from the middle and bottom of the tank. That sample is sent to a lab, we get a full report on what’s going on in your fuel tank, this report is shared with you including recommended action from the results. The report tells us which biocides we should be using, and how much to get you the best results.

Depending on your generator and fuel needs, you might need to clean your fuel more or less often. Critical backup generators, generators in harsh climates, and generators with highly contaminated fuel often require more cleaning to prevent damage and make sure they run properly.

If your Diesel is Dirty, You Run the Risk of Your Tank Shutting Down Right When You Need it Most

Clean fuel offers peace of mind, reduced downtime, and prevents damage to your generator.

Submit your information to schedule your free fuel sample. We’ll assess the quality of your fuel, tell you the risks, and get you a plan to keep your fuel clean and your generator running.

There’s no obligation, and the sample is completely free.

Schedule a FREE Fuel Sample