Your generator is only as reliable as the fuel that powers it. Even the most robust diesel generator can fail if its fuel supply is contaminated.
Water, sludge, rust and microbial “diesel bug” growth don’t just reduce efficiency; they can clog filters, corrode components, and cause total breakdowns when you need backup power most.
Fuel contamination is one of the most common and overlooked reasons generators underperform or fail altogether. The good news? With the right maintenance and monitoring, it’s preventable.
In this guide, we’ll explain what fuel contamination is, the warning signs to look out for, and the practical steps you can take to protect your long-term investment and keep your generator running for decades.
Fuel contamination occurs when there are substances in the fuel that reduce its quality. Generators rely on a fuel source to work, as it powers the engine, but excess water, dirt, rust, and other substances will clog the filters and impact the generator’s ability to work.
Most backup generators run on diesel fuel, which can be vulnerable to contamination when stored for long periods. If you don’t regularly monitor diesel fuel, contamination might damage the components and result in complete failure.
So, if your business suffers a power outage, the generator may be unable to provide reliable backup power, resulting in significant financial losses.
Understanding fuel contamination is a must for homes and businesses that rely on diesel generators.
In most cases, fuel storage tanks are a safe way to prolong the lifespan of your fuel source. However, there may be cases where contamination occurs. Knowing the common types of fuel contamination can help you identify any problems.
Water might not seem like a significant issue, but it’s one of the biggest threats to your fuel supply. Poor storage conditions, leaks, and condensation can lead to water entering the fuel tank. Once water combines with your fuel, it can result in corrosion, reduced efficiency, and microbial growth.
Microbial growth (or diesel bug growth) is when yeast, fungi, and bacteria grow in the tank. These contaminants thrive by feeding on hydrocarbons and produce acids or sludge that clog the fuel filters and corrode the tank.
Particulates like rust, dust, dirt, and other solid particulates often contaminate the fuel due to corrosion. However, they can also enter the tank during the refuelling process. Particulates often cause damage to the injectors and decrease combustion efficiency.
Diesel fuel exposed to oxygen has a higher chance of degrading. Once it begins to degrade, the fuel can form sludge and stick deposits that block the lines and filters.
If your storage tank has specific coatings or you use cleaning agents, the chemicals can contaminate the fuel supply. It also happens during cross-contamination with other fuel types. Chemicals can damage the components of your generator.
As many generator owners find, fuel contamination rarely has a single cause. Instead, multiple factors can contribute to contaminants over time, including:
Contamination doesn’t just cause problems for your fuel system; it can also damage the generator’s components and the equipment it powers. Over time, this can cause a range of issues for your business or home, including financial losses, voided warranties, and expensive replacements.
When microbial growth, sludge, and sediment build up, they can block the fuel filters. When you try to power a generator with clogged filters, it can reduce the flow of fuel, which results in the engine struggling to start or failing during the switch-on process.
Microbes and water might produce acids, which corrode the injectors, fuel tank, and other components. Unfortunately, corrosion reduces your generator’s lifespan and usually results in expensive repairs.
When stored fuels are contaminated, they won’t burn efficiently. This leads to higher consumption rates and increased emissions. Also, you’ll use more fuel, which increases operational costs and could damage your company’s reputation if you promote your practices as environmentally friendly.
When a generator frequently breaks down or requires extensive maintenance, it can increase the repair costs. Preventing fuel issues is always more affordable than fixing them.
Failing to address fuel contamination issues can cause your generator to fail, which leaves your business without vital backup power during an outage. Industrial and commercial companies will lose valuable operational time, while emergency services could risk patients’ lives.
Data centres also rely on generators, and an outage without backup power can increase the risks of breaches.
Your generator warranty may be voided if you don’t follow maintenance guidelines. So, if the generator requires repair or replacement, you’ll pay out of pocket.
Luckily, there are ways to detect contaminated fuel systems and ensure you address them before they cause extensive issues. These include:
As many businesses and homes find out, preventing contamination is much cheaper than dealing with it. You can reduce the risks of contaminants in a range of ways, but if it does happen, you should repair it before the fuel damages your generator.
One of the most important things you can do to preserve fuel integrity is to invest in regular fuel testing services. A professional team will assess the quality of your fuel and identify any early indicators of contamination.
They’ll also advise on corrective actions that reduce repair costs and ensure the generator continues operating.
There are a range of fuel storage tanks to choose from, but some are more effective than others. Older tanks often use a single-walled design, which can increase the risks of corrosion and contamination.
By choosing double-walled steel tanks or polyethene tanks, you can protect your fuel and prevent debris and water from entering.
Condensation is a significant contributor to diesel fuel contamination. However, water separators and draining systems will periodically reduce water levels, which prevents corrosion and microbial growth.
Fuel polishing is an effective strategy for cleaning your diesel on-site using filtering techniques. The process removes debris like sludge and solid particulates while clearing water from the fuel source.
You can also add biocide treatments, which reduce the risks of diesel bugs and kill off microbial growth.
You should always store diesel in a cool, dry environment with a sealed tank. Exposure to temperature changes and direct sunlight will increase contamination risks. Using a fuel rotation schedule is also a good idea.
Instead of continuously storing the same fuel in the tank, aim to rotate it at least once every year.
Generators are complex machines that require advanced knowledge. While you can perform basic checks yourself, investing in a professional generator maintenance service is best, as specialist engineers will perform in-depth checks.
Professionals will check all components and fix any issues before they become expensive repairs.
Once you know how to protect and maintain your generator’s fuel system, you can look forward to long-term backup power and ongoing peace of mind. Solent Power is an authorised distributor of high-quality diesel generators and fuel tanks that simplify storage needs.
Our experts offer a range of services, including generator installation, fuel testing, and maintenance. Please get in touch with us today to discuss your needs.
Fuel contamination occurs when substances like dirt, sludge, microbes, and water enter the diesel supply. It can lead to serious problems, including reduced fuel quality, engine damage, inefficient combustion, and complete generator failure.
There are a variety of factors that lead to fuel contamination, but the most common include damaged tanks, improper storage conditions, water infiltration, cross-contamination, and particulate build-up. No matter what caused the contamination, you must fix it immediately to prevent expensive repairs.
The main signs of fuel contamination include visible sludge, diesel that appears cloudy and dark, black smoke coming from the exhaust, odours, and engine problems. Most people only notice issues when running the generator, which is why regular testing is important.
Contaminated fuel often blocks the filters and injectors, which leads to engine damage. It can also reduce combustion efficiency levels and cause complete breakdowns.
We recommend testing your fuel every six months, but if your generator powers critical operations in a healthcare setting or data centre, testing it frequently is advisable.
Yes, in some cases. However, it depends on the degree of contamination. Biocide treatments and on-site fuel polishing can reduce the need to replace the diesel.
Yes, it can. Many warranties are only applicable if you follow the maintenance and testing recommendations. So, when fuel contamination occurs and it is preventable, you’ll usually have to pay for the repairs and replacements.
Preventing fuel contamination requires a multi-pronged approach, including investing in regular fuel testing and generator maintenance services. Water separators and biocide treatments can also preserve the integrity of your diesel.
Solent Power Ltd (Company Number 12622565) is a company registered in England and Wales. Our registered office is located at Station yard, Bowes Hill, Rowlands Castle PO9 6BP. VAT No. 363504018