Engine running rough? It could be contaminated fuel. Our mobile units carry specialist equipment to test, drain, and flush any type of fuel contamination.
Fuel contamination takes many forms — water ingress from condensation or a damaged tank seal, bacterial and fungal growth (commonly known as 'diesel bug'), sediment from degraded tank linings, or simply receiving a batch of poor-quality fuel from a filling station. Contamination can affect both petrol and diesel vehicles and often develops gradually, making it harder to diagnose than a straightforward misfuel. Our mobile team carries specialist testing and extraction equipment to identify and resolve all types of fuel contamination wherever you are.
Don't start the engine. Call us immediately for the best outcome.
Fuel contamination often develops gradually. If you notice any of these symptoms — especially after refuelling — contamination is a likely cause.
Our simple 4-step process gets you back on the road quickly and safely.
Tell us what's happening — rough idle, loss of power, warning lights, unusual smoke. We'll carry out an initial diagnosis over the phone to assess urgency.
We arrive with fuel testing equipment including water-detection paste, fuel sample analysis tools, and diagnostic scanners to confirm contamination type and severity.
We drain contaminated fuel, flush the entire system including tank, lines, and rail, and replace fuel filters. For diesel bug, we apply a biocide treatment.
We refill with premium clean fuel from our on-board supply and run the engine under observation to confirm smooth, fault-free performance.
Water contamination is the most common type — it enters through condensation in the tank, worn seals, or faulty fuel cap gaskets. In diesel vehicles, water promotes the growth of Hormoconis resinae, a fungus commonly called 'diesel bug,' which forms a slimy biomass that clogs filters and corrodes tank walls. Sediment contamination comes from degraded tank linings, rust particles, or debris from the fuel supply chain. Cross-contamination — traces of the wrong fuel type — can occur at filling stations that share storage tanks. Finally, fuel degradation happens when fuel sits unused for extended periods, breaking down chemically and forming gums and varnishes.
Diesel bug (Hormoconis resinae and related organisms) thrives in the water layer at the bottom of diesel tanks. Modern ultra-low sulphur diesel (ULSD) is more susceptible to biological contamination than older, higher-sulphur formulations. The organisms feed on hydrocarbons at the fuel-water interface, forming a dark, slimy biomass. This biomass blocks fuel filters, corrodes tank walls, and produces acids that damage fuel system components. Vehicles that sit unused for weeks or months — caravans, boats, agricultural machinery, and backup generators — are particularly vulnerable. Treatment involves draining and cleaning the tank, applying a biocide, and fitting a water separator if one isn't already present.
Our technicians carry a range of on-site testing equipment. Water-detection paste applied to a dipstick changes colour in the presence of water, indicating both the presence and approximate volume of water in the tank. Fuel samples are drawn and visually inspected for clarity, colour, and particulate matter. For diesel bug, we use test kits that detect microbial contamination levels. Our OBD diagnostic scanner reads fuel pressure data, injector performance codes, and lambda sensor readings to build a complete picture of how contamination is affecting your engine.
Our technician will begin by taking a fuel sample to confirm contamination type and severity. The contaminated fuel is then fully extracted using our mobile pump unit. For water contamination, the tank is dried and inspected. For diesel bug, a biocide treatment is applied and the tank interior is cleaned. All fuel filters are replaced, and the fuel lines and rail are flushed with clean fuel. We then refill the tank with fresh, high-quality fuel and run the engine while monitoring live data on our diagnostic scanner. The process typically takes 60–90 minutes depending on the severity of contamination. You'll receive a full report including fuel test results and work completed.
Call us now for fast, professional fuel drain service anywhere in the Scottish Highlands. Available 24 hours a day, 7 days a week.
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