Boat Fuel Tank Cleaning Tips

Like any other component on your boat, your boat fuel tank requires ongoing preventative maintenance and care. Cleaning the fuel tank can prevent sediment buildup, contamination and fungi or algae growth. Whether you perform a DIY cleaning or hire a local boat maintenance professional, you should schedule a fuel tank cleaning regularly to optimize your boat engine’s performance.

Below, we explore why boat tanks get dirty and recommend some fuel tank cleaning tips. If you have any further questions about fuel tank maintenance or general boat maintenance questions, feel free to contact Pensacola Shipyard. We are here to help you with all your boat storage and maintenance needs.

How a Boat Tank Gets Dirty 

There are several causes of a dirty boat tank. 

Sediment Buildup 

Every time you take the boat out, dirt and grime can build around the gas inlet when you fuel the tank, or dirt gets into your spare fuel system and eventually finds its way into your tank. Even with typical usage, it is possible to see sediments collecting in your tank. When this happens, you need to remove the sediment.

Poor Quality Fuel 

Poor quality residual fuel can affect the marine engine system in various ways – high-pressure rates, high temperatures, late burning/slow-burning, coke deposits or low ignition. Bad fuel can cause unburnt carbon and ash deposits to build, as well as acid corrosion and scoring. The result is a dirty engine plagued with performance problems.


Contaminants can range from foam, exhaust deposits, water vapor and rust to common dust and even engine fuel or oil. Virtually anything that comes into contact with the engine is a potential contaminant. A neglected boat fuel tank has countless contaminants. For this reason, it is essential to schedule a routine boat fuel tank cleaning. 

Fungi and Algae Growth 

Water is heavier than diesel fuel and accumulates at the bottom of a tank. No matter how well maintained the fuel tanks are aboard a yacht, there is usually some free water sitting on the tank bottom. As a rule, whenever diesel and water come into contact in a fuel tank, microbes will develop quickly. Bacteria, mold or other fungi can clog filters, leading to tank sludge and injector failure. 

Problems Caused by a Dirty Boat Fuel Tank  

Numerous problems can arise from a dirty boat fuel tank including: 

High Engine Pressure Rates 

When your boat is operating at optimal fuel pressure, it maximizes the power and fuel economy, saving you money in operating costs, maintenance and repairs. High fuel pressure can cause numerous problems such as fuel smell, low fuel economy, poor engine performance, black spark plugs or restrictions in the return line.

High Engine Temperature 

A clogged or failing fuel pump can make your boat engine overheat. The harder a boat engine works, the hotter it runs. If your engine suddenly starts to overheat and stall, yet you have plenty of coolant and no visible radiator problems, it could be a clogged or dirty fuel pump or fuel tank. 

Late/Slow Burning Fuel 

Slow-burning gasoline is at a disadvantage because some of it may still be burning when the exhaust valve opens. Consequently, unburned gasoline passes out through the exhaust. It is inefficient since any unburned gasoline gets in the way of gasoline that burns and creates power. To improve the combustion characteristics of slow-burning gasoline, you need to perform a boat fuel tank cleaning.

Carbon Deposits 

Once carbon buildup accumulates on various surfaces inside the boat engine and is left untreated, the boat loses power, becomes sluggish and causes a significant increase in emissions and reduction in fuel economy. Carbon deposits erode the mileage and performance gains expected of a diesel engine.

Low Ignition 

If the fuel pressure is low, it can lead to a hard start, stalling, hesitation or misfiring, poor fuel mileage, etc. A dirty boat fuel tank can contaminate the fuel and cause it not to fire upon ignition. The boat may crank when you turn the ignition on, but the engine will not start due to a dirty fuel supply or a lack of fuel supply.

Boat Fuel Tank Cleaning Tips 

If you attempt a DIY boat fuel tank cleaning, there are several things you need to consider. First, understand that cleaning out your fuel tank includes cleaning out flammable material. If you have questions or concerns, you should contact a boat maintenance professional in Pensacola. Cleaning your fuel tank should always be performed with safety as the primary objective. Clean it in an area that is well ventilated and avoid sparks while handling materials. Other tips include: 

  • Disconnect the fuel line and drain the tank. 
  • Use a wet/dry vacuum to suction out any loose debris in the tank or fuel line. 
  • If necessary, change the fuel filter. If not, run new fuel through it to clean out any debris or contaminants in the filter. 
  • Check for sediment, fungus, water or other contaminants. 
  • Replace any damaged or highly contaminated hoses.

You may also want to consider hiring a local Pensacola boat maintenance or repair professional to clean or replace your boat fuel tank or other components. By hiring a professional, you can feel confident that the job is done right with no damage to your boat. Also, check with your local shipyard to find out if they offer fuel. You may save time and money by fueling up at the same place where you store and maintain your boat.

Schedule Professional Boat Maintenance in Pensacola, Florida 

Pensacola Shipyard has the facilities you need to make all essential boat repairs. We offer professional boat fuel tank cleaning and provide fresh fuel for your boat. We can protect your boat components from sun exposure, maintain your engine and equipment and keep your boat clean.

Contact us today at 850.780.8441 to schedule boat maintenance services or to fuel up.