Combatting Diesel Bug Fuel Contamination

What Does Diesel Bug Look Like?

Boat engines are vulnerable to diesel bug, a common issue caused by microorganisms that live in fuel. These organisms appear slimy or jelly-like and thrive when water and fuel mix with certain bacteria.

The microorganisms consume diesel, thereby breaking it down and producing waste products. Unchecked, these waste products can build up and clog fuel lines and filters, leading to reduced engine performance. A diesel bug infestation may cause or halt engine failure in severe cases.

Causes of Diesel Fuel Microbial Contamination

1. Poor quality fuel: Low-quality fuel may contain impurities that promote the growth of microorganisms, increasing the risk of infestation.
2. Stale fuel: Over time, fuel degrades and can develop conditions conducive to diesel bug growth.
3. Water contamination: Water intrusion in the fuel system creates a favorable environment for bacteria to multiply and form diesel bug.
4. Microbial growth: Certain bacteria and fungi can grow in the fuel, causing diesel bug to form.
5. Weather conditions: Warm and humid environments provide ideal conditions for microbial growth, leading to diesel bug formation in the fuel system.

Proper Fuel Storage on a Boat

Storing diesel fuel correctly on your boat is crucial to prevent the formation and maintain engine performance.

1. Choose the right tank: Use a fuel tank with a tight-fitting lid to minimize air exposure and prevent water intrusion.
2. Keep the tank full: Maintain a full tank to reduce air in the tank and lower the risk of water condensation, which can lead to diesel bug growth.
3. Store in a dry, well-ventilated area: Ensure the fuel storage area is dry and well-ventilated to minimize moisture buildup and reduce the likelihood of microbial growth.
4. Protect from sunlight and temperature fluctuations: Store the fuel tank in a location protected from direct sunlight and significant temperature changes, which can cause fuel degradation and promote bug formation.
5. Monitor fuel quality: Regularly check the quality to detect early signs of contamination and prevent infestations.

Avoid Diesel Bug by Using Biocides

Biocides are chemicals that can help control diesel bug growth when used correctly. They are added to the diesel to kill microorganisms, preventing infestations. You should know that once infested, you must handle that differently, as the preventative biocides will not deal with the slime and sludge.

1. Types of biocides: Several brands manufacture biocides specifically formulated to prevent diesel bug growth. These include Marine 16, Wynns Fuel Biocide, Biobor JF, FPPF Killem, and Star Tron Enzyme Fuel Treatment.
2. Preventive measure: Biocides should be used as a preventative measure, not as a cure for an existing infestation. Regular use of biocides can help maintain a clean fuel system and prevent diesel bug growth.
3. Follow instructions: When using biocides, carefully follow the manufacturer’s instructions for dosage and application to ensure effective and safe use.
4. Safety precautions: Handle biocides with care, as they can be hazardous. Wear protective gear, such as gloves and goggles, and avoid contact with skin and eyes—store biocides in a secure location away from children and pets.

Keeping Fuel Levels High to Prevent Diesel Bug Growth

Maintaining high fuel levels inside the tank prevents diesel bug growth. When the level is low, there’s more space for air, which can lead to increased condensation and water contamination. Additionally, a near-empty tank can cause the diesel to stagnate, creating an ideal environment for it to flourish.

Keeping your fuel tank full or near-full can prevent excessive air and moisture from entering the tank. This reduces the likelihood of condensation and water contamination, which helps prevent growth. Make it a habit to top off your tank regularly, especially during periods of inactivity or storage.

Fuel Polishing

Fuel polishing is a process that removes contaminants, such as water and debris, from diesel. Regular polishing helps prevents infestations and maintains quality.

1. Onboard process: Fuel polishing can be performed onboard the boat, making it convenient.
2. Filtering and cleaning: During polishing, the fuel is passed through a filtration system to remove contaminants, which are drained off.
3. Routine maintenance: Incorporate fuel polishing into your regular maintenance routine to properly maintain your fuel system.
4. Professional service: If you’re uncomfortable performing fuel polishing yourself, consider hiring a professional service to ensure the process is done correctly and safely.

How to Tell if your Fuel has Diesel Bug

Awareness of the signs and symptoms is crucial for early detection and prevention of further damage. Here are some common indicators of an infestation:

1. Engine misfires: If your boat’s engine is misfiring frequently, this may indicate a problem. The bug can clog injectors, disrupting fuel flow and causing misfires.
2. Decreased engine performance: Diesel bug can reduce engine power and overall performance due to clogging of the fuel system, which restricts the amount of fuel reaching the engine.
3. Blocked fuel filters: Frequent clogging of filters can be a symptom due to the buildup of sludge and debris in the filters.
4. Cloudy fuel: A milky substance in the fuel, causing it to appear cloudy, is another indicator.
5. Fuel odour: A strong fuel odour may be a sign of an infestation, as the waste products produced by the microorganisms can have a distinct smell.

Get Rid of Diesel Bug: Drain and Replace Contaminated Fuel

Draining and replacing contaminated fuel is the first and most straightforward step in treatment.

1. Turn off the fuel supply: Before draining, turn off the fuel supply to the engine to prevent any accidents or spills.
2. Drain the fuel: Use a pump or a hand pump to drain the contaminated fuel from the tank. Be sure to dispose of the drained fuel following local regulations and environmental guidelines.
3. Inspect the fuel: Examine the drained fuel for signs of contamination, such as a cloudy appearance or sludge and debris.
4. Replace with new diesel: Fill the tank with fresh, clean diesel to ensure optimal engine performance and prevent future infestations. Consider using a fuel filter funnel to prevent debris from entering the tank during refuelling.
5. Monitor fuel quality: Keep a close eye on the quality after replacement, and follow best practices for diesel storage and use to prevent future infestations.

Clean Fuel Tank and Fuel System

Cleaning the fuel tank and system after draining and replacing contaminated fuel is crucial to prevent future infestations.

1. Choose a cleaning method: Select a suitable method for cleaning the fuel tank and system, such as high-pressure hot water, ultrasonic cleaning, or chemical cleaning agents. Each method has advantages and requirements, so consider your specific circumstances and the manufacturer’s recommendations.
2. Take safety precautions: Wear appropriate protective gear, such as gloves and eye protection, when handling cleaning agents or equipment. Ensure your working area is well-ventilated and free from ignition sources to prevent accidents.
3. Clean the fuel tank: Thoroughly clean the tank to remove any residue or sludge left behind by the diesel bug. Be sure to reach all corners and crevices to ensure a thorough cleaning.
4. Clean fuel lines and filters: Inspect fuel lines, filters, and other fuel system components. Replace damaged or heavily contaminated parts, such as clogged filters, to ensure optimal fuel flow and engine performance.
5. Follow manufacturer’s instructions: Adhere to the manufacturer’s guidelines for cleaning your specific fuel system and tank. This will help ensure the cleaning process is effective and safe for your boat.