How To Clean A Boat Fuel Tank

Written by Paul

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How To Clean Boat Fuel Tank | Boat Seats Cleaning Products | Fuel Tank Cleaning Company/Service | Video: Cleaning Boat Fuel Tank

Every boat owner will go through the task of cleaning the boat fuel tank at some time. But how do you clean the tank properly without water contamination? 

Or... how do you figure out the rust removal process when your fuel tank is full?

These are common questions most vessel owners will have at some stage. Luckily, cleaning out a boats fuel tank is a relatively simple process once done correctly.

Before we get into the step by step guide to boat fuel tank cleaning, you'll need some marine fuel products and general special cleaning products as part of a regular cleaning schedule.

These instructions apply to boat owners of:

  • Small Motorboats
  • Sailboats
  • Pontoon Boats
  • Yachts
  • Jet Skis
  • Speed Boats

Keep in mind that specific boat fuel tank cleaning instructions can vary with some of the trickier inboard motors being more challenging in particular.

Try scrubbing the tank bottom in some of those boats!

The goal is to have a sparkling clean tank and remove any fuel-tank contamination. This is a really important part of cleaning your boat.

Boat Fuel Tank Cleaning Products You'll Need

Before you even begin to clean your fuel tank, you'll need to ensure you have some gas tank treatments and other marine specific products.

This will ensure a clean fuel management system, rust removal, vent and fill hoses hoses are spotless and the boat engine is running effectively.

There's nothing worse than contaminated fuel or any form of dirty fuel for that matter. Here are some of the marine industry recommended products:

  1. Fuel/ Oil Absorbent Pads
  2. Pressure Washer
  3. Water Filter
  4. Fuel Filter
  5. New Marine Engine Fuel
  6. A Suction Hose/Pump
  7. A bucket

When you have your products ready, you're set to get those fuel tanks squeaky clean. If you haven't cleaned out the tank before, you'll be surprised the dirt that builds up especially at the tank bottom.

Right, let's get into the steps to take for good tank care.

Step 1: Draining The Fuel Tank

fuel tank cleaner

First thing is you'll want to drain the fuel tank. You can use a suction hose/pump (shown in the products image) or simply use a bucket and a hose as shown in the image.

If you're boat engine isn't complicated and you can easily access the fuel tank, then this is a cost effective way of emptying it.

Now, if you just the simple bucket and hose option, you will only remove the fuel. The suction pump will remove the bulky and harder to remove items that otherwise would be missed.

You might need to use a bleach cleaning product if the boat seats are particularly dirty with water damage but don't use it as part of your regular deep cleaning.

Ideally, you'll get some good-quality cleaner and it won't cost too much.

Step 2: Isolate The Lines From Tank To Boat Engine

Next up, you'll want to make sure you've isolated the lines. We do this to stop any leakage of fluids, fuel-tank contamination or any waste oil leakage.

While you are doing this, now would be a good time to remove some of the old filters. They don't always have to be replaced but if they are particularly bad/dirty, it's worth changing filters.

Isolating the lines is important if you plan on using a pressure washer to clean the fuel tank (see step 3) 

You can read about how to isolate the lines from our winterizing a boat engine article.

Step 3: Cleaning The Fuel Tank (Dirt/Rust Removal)

gas tank treatments
credit: thecoastalpassage.com

Now, the import stuff. Once you've used the pump the remove any fuel from the boat tank, you can use it as a vacuum to hoover up any dirt, residue or unwanted material.

You'd be surprised what you can find and it's always best to give it a thorough vacuuming.

Next up, you have two options. Use a hot pressure washer to blast any hard to get areas. Do NOT attempt this without having all the connecting lines disconnected first.

Alternatively or after you pressure wash the fuel tank,you can use either a sea foam cleaner or fill your tank with isopropyl alcohol and let it sit for a while to dissolve all the residue.

Then clear the tank out again and let fresh air into it for a bit.

To summarize this: 

Use Pump To Remove/Drain Fuel From Tank

Use Hot Pressure Washer To Blast Any Dirt Out

Use Sea Foam Cleaner To Dissolve Any Remaining Residue

Clean or Replace Fuel Filters

Once we've done all those steps we move on to the reattaching.

As an extra tip to be aware of, if you decide to use a pressure washer to clean out the fuel tank and can't fit the washer head into the tank, there are specific power washer nozzles you can get from Amazon to tackle those tricky areas.

We haven't personally used these so we cannot say how effective it is but some our community find it very helpful.

Step 4: Reattach The Fuel Tank Hoses

boat fuel tank hose
credit:boatus.com

Once you have everything looking spotless and you have the boats fuel tank dried out. (it's super important to have the tank empty of any fluids) you can go about reattaching the fuel lines and hoses.

Remember if you haven't cleaned the tank in some time to ensure the hoses/filters are spotless too. Otherwise, all your hard work may have been wasted.

Step 5: Fuel Tank Care

As part of regular cleaning of the fuel tank, you can use cleaner and more efficient fuel to ensure the tank stays in great shape.

Just be very aware of what you are putting in the tank. Cleaning out a fuel tank doesn't have to be done every month. But it's best to do it once a year, ideally when you are not using it during the winter months.

Step 6: Use Clean Fuels

clean boat fuels
credit: gotpower.com

Whether it's Diesel engine clean fuel or any other gasoline marine engines fuel, it's good practice to feed your boat engine with the fuel it needs.

This will have lots of benefits including improved boating performance, it will help with fuel-system maintenance. Just look at the image above to see the obvious difference a cleaner fuel tank will have on the fuels versus a dirty one.

Disposal Of Fuel Tank Oils/Fuels When Cleaning

When you are finished and need to dispose of the waste. Be smart about it. Take the necessary precautions and dispose of waste oil, dirty body of water and the oil absorbent pads in the correct recycling centers.

This can get messy fast so it's important to do it right.

Boat Fuel Tank Cleaning Company/Service

If you aren't technically minded or would just prefer to outsource the process to a professional, you have a number of options.

You can hire a Fuel Tank Cleaning Business to come and do the work. A simple google search in your local area and you'll find what you need.

The price for this service varies a lot and will depend on your specific area but it should cost minimum $200+

Alternatively, you may find a service on Craigslist to do this but just be wary and do due diligence as craigslist can be hit or miss.

How To Clean A Boat Fuel Tank (Video Instructions)

Below is a video from thatboatguy on a simple diy version of cleaning your boat fuel tank.

As you can see, it's relatively easy to do and you'll be done in no time.

Other Boat Cleaning Guide