Boat Fuel Tank Cleaning


There’s nothing more relaxing than cruising in your boat with the sun and salty water in your face. But, that smooth trip might not be so smooth if your fuel tank is dirty.

Lucky for you, you won’t need to call in a professional or pay copious amounts of money to keep it clean! Instead, you can easily clean your boat in six simple steps that will take no time. 

Different models of boats will require slightly different processes, so we created a personalizable guide. 

We’ll also cover all you need to know about the materials and tools required.

Why Clean Your Boat Fuel Tank?

A dirty fuel tank can cause many risks to your boat. Fungi and algae can build up, which deteriorates your tank faster and clogs up your carburetor. 

So, it’s essential to keep it clean.

Safety Precautions for Cleaning Your Boat Fuel Tank

Since you’ll be dealing with fuel, you’ll need to take certain precautions to ensure the safety of yourself and the boat.

First off, make sure your boat is in a well-ventilated area out of water. You don’t want to be moving around while you clean your fuel tank. 

Then, close off any ignition sources. Since you’ll be handling fuel in a closed space, you don’t want to risk igniting it because it can lead to severe injuries. 

A good precaution you can take is to ask a friend to help and wear personal protective equipment (PPE). Wearing PPE will protect you from most hazards. You should wear:

  • Chemical-resistant gloves
  • Safety goggles
  • Overalls 

A good tip is to also wear old clothes because fuel is highly pungent, so the scent will stay on your clothes for a while.

What You’ll Need:

  • Siphon pump
  • Sieve
  • Bucket 
  • Pressure washer
  • Water 
  • Soap
  • Commercial cleaner
  • Isopropyl alcohol 
  • Towel 
  1. Emptying the Tank

Start off by draining all the remaining fuel in your tank. A good tip is to plan your cleaning according to when you empty the fuel out by using it. 

Draining the fuel is important because it makes the process safer and easier. Before you try to suck out the fuel with a hose like you might’ve seen in the movies, stop!

Not only will you leave a horrid taste in your mouth, but you might risk choking yourself or spilling some gasoline. Instead, invest in a convenient yet affordable siphon pump

Not only does it transfer the fuel, but it also pumps out some of the sludge deposits in the bottom of the tank. Still, there will be leftover sludge that you’ll be cleaning out later.

Because gasoline prices are crazy these days, you’ll want to empty the fuel into a bucket and keep it safely stored until you finish cleaning the tank.

  1. Isolating the Line

Isolating your fuel line is a simple but important step. You can find the specifics on doing it in your boat’s manual because the process varies by model.

Isolating the line prevents two main things:

  • Leakage of any fluids from other lines
  • Leakage of cleaning water from your tank to the engine.

Any leakage from other lines will risk the safety of your tank as well as other parts. Moreover, getting water on your engine could ruin it, which will cost you a lot of money to repair or replace.

  1. Remove the Tank (Optional)

Some models don’t come with removable tanks. So, you can definitely skip this step if your tank is non-removable.   

Removing the tank is preferable because you won’t risk getting any other boat parts contaminated, and you can ensure that no fuel will come into contact with anything unsafe.

Before you do so, check your boat’s manual to determine whether the tank is removable or not.

If you remove the tank, leave the valves in place, so you don’t need to readjust them when you pop the tank back in. This saves you a lot of time and effort.

  1. Clean the Tank and Other Sections

Now let’s get to the cleaning! To make sure your tank is as clean as it possibly could be, you’ll need to do three things. 

First, clean your tank using a pressure washer to get rid of all the dirt. If your tank is really deep, you might need a special nozzle to fit into the tank. The lowest setting of the pressure washer is more than enough to do the job.

Then, fill up ¾ of the tank with isopropyl alcohol to dissolve all the gunk out, even on the smallest of edges. Empty the tank with a siphon pump after 2 hours to give the alcohol time to completely dissolve the gunk. 

Lastly, do the same thing with some soap and water for finishing touches. As you empty the soapy water, use a makeshift sieve to see the particles exiting the tank. 

When the particles stop showing up in the sieve, that’s how you know the tank is clean!

Cleaning the gas tank is not all you need to do. You also need to make sure that the surrounding areas are also clean. Wash the following items:

  • Carburetor 
  • Intake valves
  • Combustion chambers
  • Fuel lines

This ensures that the whole thing will be squeaky clean!

  1. Switch Out the Filter

If you want to go the extra mile and ensure that you’ve cleaned your fuel tank from all waste, you can install new filters

This will bring your fuel tank back to its peak condition because the filters collect dirt and debris over time.

This debris affects your boat’s fuel consumption and may hinder its overall performance.

  1. Wait for It to Dry and Reattach the Tank

It’s important to ensure that the tank is completely dry, so the water doesn’t mix in with the fuel or get into the engine and ruin it. Leave the tank to dry for a few days.

If you’d like to speed up the process, use a lint-free towel to dry it. 

Then, reattach the tank, fuel lines, and fuel hoses. Put everything back into its original place and fill your tank back up with fuel as you normally would.

Before you start cruising, start your motor up and leave it running for a few minutes to make sure everything is working fine.

And there you’ve got it! A perfectly clean tank.

Tips for Cleaning Your Boat Fuel Tank

Cleaning your gas tank can be much easier and more efficient if you use these simple tips:

  • When removing the fuel from the tank, place your boat on an incline, so the fuel piles up in one corner. This makes removing the fuel easier.
  • Use clean fuel in your tank to avoid inflammations and dirt build-up. 
  • Clean your tank routinely once a year, so the tank stays somewhat clean all year round. The longer you wait between cleanings, the harder it will be to clean.
  • Clean the gas tank before you store your boat away for a while. This prevents fuel phase separation

Final Thoughts

Although cleaning your fuel tank can be worrisome, following the precautions in this guide will ensure your and your boat’s safety.

Once you get the hang of it, you’ll find your autopilot kicking in, and you’ll be done in no time! As we mentioned, getting the help of a friend helps in several ways; it’s always good to have company in case you need an extra pair of hands.

Soon enough, you’ll be back cruising on the water without a single worry in mind. We wish you a positive cleaning experience and an even better boating one!

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