Winterizing Your Boat: Gas Tank Maintenance

When preparing your boat for winter, it is important to winterize your boat's fuel tank to prevent issues that may arise from fuel being left sitting for a long period of time. There are several methods to do this, including filling up your fuel tank, adding a fuel stabilizer, and changing your fuel/water separator.

Fill the tank with fresh fuel

Filling your boat's tank with fresh fuel before storing it for winter is a good idea. This is because, over time, fuel can begin to "go bad" and oxidise, forming a gum-like substance that settles in fuel lines and tanks, carburetors and injectors. This can cause issues when you try to burn the fuel, as deposits may form in the combustion chamber, reducing your engine's performance.

The first step in preparing your boat for winter storage is to plan your late-season boating so that you use up most of the current fuel in the boat's tank. Then, fill it with fresh fuel just before it's prepared for storage. It is recommended to use gasoline that does not contain ethanol if that product is available where you live. This is because ethanol can create issues with your fuel system, degrading the insides of fuel hoses and lines, causing particles of rubber and plastic to clog injectors and carburetor jets.

Additionally, ethanol has a tendency to mix with water. If more than 500 parts per million of water get into the fuel, it can bond with the ethanol and sink to the bottom of the tank. This is called phase separation, and it can cause significant damage to your engine. By using ethanol-free gasoline, you can help to prevent this issue.

When filling your tank for winter storage, it is also important to add a marine-specific fuel stabilizer additive to the fuel. Follow the instructions on the bottle to ensure proper usage. After adding the stabilizer, it is a good idea to take the boat out for a short run to distribute the treated fuel throughout the fuel system. This is especially important for boats with gasoline outboard, sterndrive, or inboard engines equipped with a carburetor.

By following these steps and filling your boat's tank with fresh fuel before winter storage, you can help ensure that your boat will be ready to go when the next season comes around.

Use non-ethanol gasoline

When preparing your boat for winter, it is important to use non-ethanol gasoline. This is because ethanol is a solvent that can dissolve fiberglass fuel tanks, as well as react with fuel filters and carburetors. It also attracts water, which can lead to water contamination or fuel phase separation, causing issues with your boat engine.

To avoid these problems, it is recommended to use non-ethanol gasoline when filling up your boat's gas tank for winter storage. This type of fuel is typically more expensive, but it can save you money in the long run by preventing costly repairs. It is also important to keep your boat's fuel tank full during winter storage, as this can help to reduce the amount of condensation that forms inside the tank.

Additionally, proper fuel treatment is key when preparing your boat for long-term storage. This includes using a quality fuel stabilizer additive that is marine-specific and does not contain alcohol. Following the instructions on the product, you should add this stabilizer to the fuel as you fill the tank. It is also a good idea to give the boat a short run on the water after adding the stabilizer to distribute the treated fuel throughout the fuel system.

By taking these precautions and using non-ethanol gasoline, you can help ensure that your boat will be ready for use when the next season comes along.

Add a marine-specific fuel stabiliser

Adding a marine-specific fuel stabiliser is a crucial step in preparing your boat's gas tank for winter. Fuel stabilisers are designed to slow down the natural breakdown of gasoline, which can occur within a matter of months if left untreated. This breakdown process is known as "going bad", "going stale" or "varnishing", where some fuel components begin to oxidise and form a gum-like substance that settles in fuel lines, tanks, carburetors and injectors.

When choosing a fuel stabiliser, it is important to select one that is specifically designed for marine use, such as Techron Marine by Chevron. Follow the instructions on the bottle and add the recommended amount to your fuel tank. This will help to ensure that your fuel remains stable and fresh during the winter months.

Marine fuel stabilisers also play a critical role in preventing issues caused by ethanol in marine fuel. In most states, all gasoline sold contains ethanol, which can create problems for your fuel system. Ethanol has a tendency to "eat" or degrade the insides of fuel hoses and lines, leading to clogged injectors and carburetor jets. Additionally, ethanol readily mixes with water, and if more than 500 parts per million of water are present in the fuel, it can cause phase separation, resulting in a loss of octane and potential engine damage.

By using a marine-specific fuel stabiliser, you can help to prevent these issues and protect your boat's fuel system during winter storage. It is also recommended to use gasoline that does not contain ethanol if it is available in your area.

It is worth noting that fuel stabilisers should be used in conjunction with other winterisation steps, such as filling up your fuel tanks to minimise condensation and changing your fuel/water separator. Proper fuel treatment and winterisation are key to ensuring a smooth start to your next boating season.

Run the engine to distribute the treated fuel

Running the engine for a short period is an important step in preparing your boat's gas tank for winter. This process helps to distribute the treated fuel throughout the fuel system, ensuring that the stabiliser reaches all parts of the engine.

It is recommended to run the engine for around 10 minutes, which should be enough time for the treated fuel to circulate. This is especially crucial for boats with gasoline outboard, sterndrive, or inboard engines equipped with a carburettor. Carburettors are particularly susceptible to issues caused by untreated fuel, which can quickly oxidise and leave behind deposits that cause problems when starting the boat in the next season.

The process of running the engine to distribute treated fuel is also essential in preventing issues caused by modern gasoline, which can go sour in just a few weeks, especially if it contains ethanol. Therefore, it is a good practice to stabilise boat fuel throughout the season, not just during winter preparation.

By following this step, you can help ensure that your boat's engine will be protected during the winter storage period and be ready for use again in the next season.

It is worth noting that, in addition to running the engine, other steps are crucial for properly winterising your boat's fuel tank. These include using up most of the current fuel, filling the tank with fresh, non-ethanol gasoline, adding a marine-specific fuel stabiliser additive, and following the instructions on the stabiliser product.

Leave a little capacity for fuel expansion

Leaving a little capacity for fuel expansion is an important consideration when preparing your boat's gas tank for winter. Here are some detailed explanations and instructions regarding this topic:

• The normal daily temperature changes, with cooler evenings and warmer days, as well as fluctuations over the six-month off-season, cause the air in the fuel tank to expand and contract. This "breathing" of the tank through its vent can draw in damp air during the winter, leading to condensation issues.
• By leaving a little capacity for expansion, you ensure that there is room for the fuel to expand without causing damage to the tank. This is crucial for the health of your boat's fuel system.
• While filling the tank almost full is recommended to displace air and prevent condensation, it is essential to leave some space to accommodate the expansion of fuel when temperatures rise.
• The expansion damage can occur if the fuel tank is completely filled and not allowed to breathe. Therefore, finding the right balance between minimizing condensation and allowing for expansion is key.
• Additionally, capping the fuel tank vents is not advisable, as it can restrict the tank's ability to breathe and lead to potential damage.
• It is worth noting that different boat owners and experts may have varying opinions on the ideal fuel level for winter storage. Some prefer to keep their tanks full, while others opt for a quarter or half tank. However, the general consensus is to leave a little capacity for expansion to avoid any potential issues.

Frequently asked questions