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How to Drain Gas From Boat Fuel Tank? Start to Finish!

Written by Anthony Roberts / Fact checked by Jonathan Larson

Sailing off-season gives you enough time to inspect what needs to be done on your boat. One concern that you would likely have is the residue buildup on the fuel tank. So, how do you prevent it?

How to Drain Gas From Boat Fuel Tank

The solution to revert your fuel tank to its clean stain is by draining. Doing it by yourself can help you cut the expenses. To start, you may be asking yourself, ‘How to drain gas from boat fuel tank?’.

For this process, you just need to follow this article to earn skills in emptying your boat’s fuel tank. As a result, you can keep your boat in good shape like a pro.

Necessary Materials You’ll Need


  • Work Gloves

Draining the gas out of the fuel tank by yourself entails you to use bare hands. However, some may think the greasy gas is unpleasant. So you have to use work gloves to avoid feeling it for real and maintain the cleanliness of your hands.

When buying gloves, put them on and move your hand and your fingers to ensure they are the right ones for you. You must be comfortable when wearing them so you can handle the materials well.

  • Eyewear for Protection

Gas is not something you can take as a joke as it can be dangerous, especially to your eyes. Thus, there’s no excuse to not wear eyewear for protection. Goggles are fine for this preventive measure.

  • Face Mask

Although your nose is not sensitive to gas odor, it’s still advisable to wear a mask. It’s not good to keep sniffing on it.

  • Fuel Hose

The ideal fuel hose to use in this job is the one with a 3/8-inch thickness. You can buy a 6-foot hose and cut it into two. So you can put drainage for both sides with a 3-foot hose each.

You can use a hose that differs from the said size to conform to your boat’s structure. Boats vary in size as well as having different fuel tanks. Therefore, it’s on your end to measure.

  • Primer Bulb or Fuel Transfer Bulb

A primer bulb allows manual operation. You can draw gas from the tank by pressing it down. The process requires your fingers and hands to exert effort in extracting the fuel and other substances.

Some may find it inconvenient to do the pressing frequently. But this is less expensive than the other method and you don’t need to make it work.

There’s no need for manual pumping if you get the fuel transfer bulb. However, the cost comes along with the ease and comfort that it offers. Power is needed to start its operation.

The procedure is a breeze with the fuel transfer bulb. But it would help if you still need to look at how it drains the fuel from the tank the whole time.

  • Hose Clamps

Getting the gas from the tank can be messy due to leaks. To prevent this from happening, you need to add the hose clamp either to the fuel transfer bulb or primer bulb.

There might be a specific clamp for the one that you’ll select with the two bulb options. So better research before buying.

  • Screwdriver

This tool shouldn’t be absent as you need it to tighten the clamp and the hose together.

  • Fuel Receptacle

Once the gas comes out of the tank, it will proceed to the fuel receptacle.

Guide on Draining Gas from Boat Fuel Tank


  • Running the Boat on the Water

Start by turning on the boat to run over the water. Doing so will deplete the fuel that’s inside the engine. But you have to leave 1/8 of the fuel in the tank. Using a water muff is another option for this step.

  • The Boat Shall Leave the Water

Turn off the boat when the running is over and leave the water. You can place it on a trailer to be taken to a level area.

  • Wearing Protective Garments

Upon arrival at your preferred location, you have to wear protective garments such as work gloves, a face mask, and protective eyewear.

  • Connecting the Hose to Primer Bulb or Fuel Transfer Bulb

Two things can happen when doing this step. Simply, you can just connect the hose to the fuel transfer bulb. However, you may need a connector in some cases.

On the side of the primer bulb, it’s straightforward as tightening it with a hose clamp will do. However, you may need the help of a screwdriver.

When connecting the other end of the hose to either primer or fuel transfer bulbs, secure the clamp with a screwdriver.

  • The Hose Should be Attached to Fuel Receptacle

After connecting it to the pump, the other end of the hose should be attached to the fuel receptacle. It gives way for the boat to catch the drainage derived from the fuel tank.

  • Hose and Fuel Tank Together

You have to take off the tank’s cover and make sure that the hose reaches the bottom of the container.

  • Draining the Tank

This is the part that you have set up everything. If you choose a fuel transfer bulb, all you need to do is to turn it on and poof! It works on its own.

When utilizing a primer bulb, you have to squeeze it firmly to stimulate draining. Then, you have to keep on pressing until all the fuel is ejected.

  • Last Step

After you drained your boat’s fuel, close the tank and remove the hose. You have to be responsible for gas disposal and aftercare. Next, you can put the boat back to its trailer and put it in storage.

Draining the Fuel Tank Includes Cleaning Too

After emptying the fuel tank, you can use the pump as a vacuum to suck in the dirt, residue, and unwanted particles. You have to be thorough as some things might surprise you.

Any hard-to-reach areas would be well taken care of by a hot pressure washer. Disconnect the lines first when you drain the tank.

The next thing that you have to do after pressure washing is filling your tank with isopropyl alcohol or seafoam cleaner. Any of these substances can break up the residue.

You can let fresh air come into the fuel tank for a short while after getting rid of unnecessary elements. By spending some time cleaning up the tank, draining the fuel will be uncomplicated in the future.

Some Pro Tips

  • Make sure that you don’t drain your boat’s fuel tank near flammable things.
  • You can turn the fuel tank upside down to check if there’s remaining gas or particles. Some tilt the boat at an angle that gives ways to drain the tank.
  • Securing a fire extinguisher can be a part of your preparation. So it will be on hand in case of emergency.
  • Installing a new filter is a simple step, but many boaters tend to forget about it. The old filter curtails the fuel flow, giving you a hard time draining the fuel tank.

Start Working on Your Fuel Tank Like a Pro Now!

Since you know now how to drain gas from boat fuel tank, there’s no need for you to hire professionals. The steps are simple as long as you’re extra careful with your actions because you deal with gas.

It’s good to go back to the waters and sail with a clean fuel tank. You should know the importance of this process as it prevents damages from developing on your boat. Besides, you also can refer more to marine fuel stabilizer or ethanol fuel treatment. And after going through this article, if you have any thoughts or comments, feel free to type it down. We love hearing from you.

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