Did you know that boat fuel is perishable?
Boat fuel comes loaded with additives. When left sitting for too many months, the components start to separate out, leading to a gunky sludge at the bottom of the tank.
E10 marine gasoline is also typically composed of 10% ethanol, which can quickly lead to oxidation and corrosion in the inside of your engine.
While fuel stabilizers can help to slow down these effects, you should still plan to clean out your boat’s gas tank routinely, especially when it’s dormant for more than a few weeks. At the very least, you’ll want to clean your boat gas tank every six months.
Here, we’ll tell you exactly what you’ll need, and give you specific, step-by-step instructions for cleaning out your boat’s gas tank. (If you want to know how to clean out the rest of your boat, check out this article.)
Essential Tools for Cleaning Your Boat’s Gas Tank
The key items for this task include:
- Siphon pump – for safely removing gas from the tank
- Fuel container – for storing and recycling removed gas
- Gas tank cleaner – commercial product that helps remove any gunk or buildup
- Pressure washer (optional)
- Safety gear – gloves, glasses, a face mask and long sleeves/pants
The hardest part of this entire process might just be keeping the smell of gas off your clothes and hands. Gloves will help, but even a tiny amount of gas has a penetrating smell.
(You’ll find a range of DIY options for getting rid of gas odor online…but it’s easier to avoid a gas spill than to clean one up).
1. Use a Siphon Pump to Remove the Gas
You’ll want to clean out your tank outside. Gas fumes trapped in an enclosed space can make you sick.
Do a brief inspection of the area around your boat for any fluids or materials that could ignite gas. For example, marinas are often lined with extension cords. (Also, avoid places where someone might step outside to smoke – like outside the bar at the yacht club.)
You’ve probably seen someone get a siphon going by sucking on it. For many good reasons – including the fact that gas is toxic – this is not a good idea.
You should use a siphon pump, which is basically a tube with a pump attached. You’ll minimize spills and the chance of getting a mouthful of sludgy E10.
(Do your best to avoid electric pumps: Sparks and gasoline don’t play nicely).
Pro Tip: With some boat models, it may be easier to remove gas by leaning the boat at an angle. Consult the owner’s manual before tilting, as you’ll need to approach this maneuver differently depending on model-specific considerations.
2. Carefully Siphon the Gas from your Boat’s Fuel Tank Into the Container(s)
Only use containers specifically designed for gas. A 5-gallon container is typical. You’ll have to do the math in terms of figuring out how many containers you will need.
Disposing of old gas safely and in an environmentally responsible manner is very important. Check out this article for instructions.
3. Disconnect, Clean & Inspect Fuel Lines
After draining the fuel tank, you’ll want to disconnect the fuel lines (consult your owner’s manual if you don’t know your way around your boat’s fuel lines).
Disconnecting prevents any contamination and ensures optimal fuel flow during the cleaning process. Once the fuel lines are disconnected, inspect them for any signs of dirt, debris, or damage.
To clean the fuel lines, use a lint-free towel or cloth to wipe away any dirt or residue. If necessary, replace any damaged or worn fuel lines to ensure proper functioning and prevent future issues.
4. Remove the Boat Fuel Filter
Your fuel filter removes particles and unwanted grime from your tank. You can find out where it is located, and how to remove and install it, in your owner’s manual.
5. Apply Boat Fuel Tank Cleaner
For an effective gas tank cleaning, follow these steps:
- Apply a boat fuel tank cleaner. (Sea Foam is the Heinz 57 Ketchup of engine cleaners: It’s not the only option, but certainly the most ubiquitous.)
- Pour the cleaner into the tank and let it sit for the recommended time, usually 15-30 minutes.
- Use the siphon pump to drain the cleaner and any remaining liquid from the tank.
- Continue this process until the siphon is no longer capturing any small particles.
6. Flushing and Rinsing the Fuel Tank
Next, you’ll want to make sure all debris and cleaner residue are removed from the tank.
Pro tip: You can also use a pressure washer for a more thorough cleaning.
Once the tank is thoroughly rinsed, use a siphon hose to remove the water. Repeat this process until the water runs clear, ensuring all cleaner residue and debris are removed.
7. Dry Out the Fuel Tank
Ideally, you want your newly cleaned tank to completely dry before moving on to the next steps. Many factors (sunlight, humidity, hours at your disposal) can limit your ability to thoroughly dry out the tank. If nature’s working against you, aim to dry out your fuel tank as much as possible.
Waiting for your tank to air dry for a few hours is a good time to carry out other forms of boat maintenance.
Pro tip: A shop vac can be used to manually dry out the tank.
8. Reinstall the Fuel Filter
You have two options at this point: you can clean out the fuel filter or replace it with a new fuel filter. Some boaters say you should change the fuel filter after 100-300 hours of use. (Check your owner’s manual and the fuel filter instructions for your specific boat model.)
Since fuel filters are cheap, and you’re already putting all of this time and effort into cleaning out your fuel tank, a replacement isn’t a bad idea. It can only help your engine’s efficiency.
9. Reconnect the Fuel Lines
Your engine won’t work without connected fuel lines. If you want to avoid squirting a bunch of gasoline all over your engine, your boat, or your person, double-check that you’ve reconnected the fuel lines.
10. Fill ‘Er Up
The one time you want to fill up carefully is when your boat is going into long-term storage – especially in sub-zero temperatures. Water in your fuel tank can do harm over time – especially if it freezes. (Check out our guide: How to Winterize Your Boat.)
There are two ways to avoid this. First, you want to fill the engine up as much as possible, leaving minimal room for air. Secondly, you’ll want to use a fuel stabilizer to reduce the amount of fuel decay.
11. Idle the Engine for 10 minutes
After allowing the engine to run for a few minutes, you’ll want to inspect a couple of things. First, check the system lights to see if any warning lights come on. Second, carefully inspect all areas around and below the fuel system for any leaks.
Troubleshooting Common Boat Gas Tank Issues
Clogged fuel filters are a common issue that can hinder your boat’s performance. The boat’s fuel filter sifts out impurities and debris from the fuel before it reaches the engine. If the filter becomes clogged, you’ll notice the following symptoms: difficulty starting the watercraft, stalling, or inconsistent acceleration.
Another common issue that can impact your boat’s performance is reduced fuel flow. Blockages or restrictions in the fuel lines, fuel filters, fuel pumps, or fuel injectors can cause this problem.
Fuel system issues often manifest as engine sputtering, which can be a source of frustration for boat owners. To address this problem, assess the fuel gauge, inspect the fuel system, and check for any leaks.
Now That Your Boat’s Gas Tank is Clean and Mean…
If you’ve followed the 11 steps detailed above, your tank should be nice and clean. The only thing left to do is schedule your next cleaning. Regular cleaning will pay off with higher fuel efficiency.
If you’re cleaning your boat’s gas tank with the intention of putting your boat into storage, Neighbor has you covered with local, safe, and convenient storage spaces to store your boat. Cleaning your gas tank out and storing your boat in a good location are two ways to keep your boat healthy and happy.
