Fuel Testing for Backup GeneratorsBusinesses and institutions with backup generators need them to be operational at all times so that you can turn them on at a moment’s notice. Preventative maintenance is an essential part of readiness. Many backup generators are primed and ready to go, with fuel left in them. They will start immediately when you power them on, restoring power to the business until the power grid is operational.

Bad fuel can not only prevent a backup generator from running; it can actually cause harm to the internal generator parts if run through the generator. Fuel testing and sampling are a vital part of the annual maintenance performed on backup generators to ensure they will run at peak performance.

Testing for fuel stability and quality on a standby generator requires various elements.

Moisture Detection

One disadvantage of leaving fuel in the generator is the risk of moisture compromising the fuel. If moisture enters the fuel tank or other parts, it can prevent the generator from running when needed.

A few sources can create moisture in the fuel tank, such as an error during fuel delivery, condensation from the weather, and leaks. Once the technician detects moisture, they will work with their team on a resolution.

Bacteria Detection

Fuel testing will also determine if any bacteria are lurking in the fuel. Though bacteria cannot thrive in diesel fuel, they can if water is present. Bacteria love biodiesel, which may be part of the backup generator’s diesel mix used to operate. If bacteria are present, they can destroy the generator’s fuel system. Detecting bacteria will allow the technician working on the generator to provide the correct type of fuel treatment to kill the bacteria.

Oxidation Stability

Another part of the fuel test is oxidation stability, as generator fuel does not have a long shelf life. With up to 5% of biodiesel allowed in the diesel fuel, the already short shelf life is even faster. If the technician measures the stability of the fuel and it’s oxidized, they can then treat the fuel to extend its life cycle.


Another essential part of the fuel testing process is checking fuel filters for particulates. Fuel filters in a standby generator work the same as in a car or home. They keep the fuel clean by filtering out particulates and other matter to ensure the generator stays operational. If the technician finds particulates, the technician can replace the fuel filter, and reach out for additional support.

Fuel Testing for Your Backup Generators

Regular maintenance, including fuel testing, is critical to ensure your backup generator is working at all times. The Building Maintenance team at BMSI in Washington, D.C., is trained in all aspects of backup generator maintenance. Contact us today to learn more about BMSI and our solution for your building maintenance needs. We’re working better together every day!