How to Clean a Fuel Transfer Tank

A fuel transfer tank is a great solution when you need to haul a little extra, but you may find yours in need of cleaning at some point. Knowing how to clean a dirty tank — and when to throw in the towel — can help protect and extend the life of the engines your fuel ends up in.

Your approach will depend on what condition the tank is in, but your tank must be drained regardless, and any discarded fuel must be disposed of in compliance with all environmental regulations. Simply empty the old fuel into a government-approved container, contact your city waste management, and ask where to dispose of it. Once the transfer tank is empty, you can move on to assessing its condition and cleaning it. In case it isn’t clear, do NOT pour old fuel on the ground or down a drain.

Clearing Debris, Water and Contaminants

Tanks that have been left to sit for long periods or refilled many times have likely accumulated some amount of debris, water or even some live fungal cultures. To regain use of your tank, it will need to be cleaned out thoroughly.

You have a few options here. First, you could ask a local radiator shop if they can perform a steam cleaning on the tank. For a more DIY method, if the tank wasn’t too dirty, you can slosh soap and water around and then drain it from the container. For very dirty tanks, try using a diesel fuel biocide, and make sure to coat the walls.

In any case, always ensure the tank is fully drained and dry before fuel is reintroduced, and install high quality filters to protect the pump. Be prepared to check and change the filters more frequently after a cleaning to clear out any residual debris.

Switching From One Fuel to Another

If you want to swap your gas tank for diesel or vice versa, you’re in luck. The chemical makeups of both fluids are similar enough that this isn’t a huge chore, but it’s still a good idea to do a light clean in between.

After draining the old fuel and checking to make sure there’s no additional contaminants to contend with, a light soapy water will do. No need to go full steam clean or chemical bath — just make sure all the water is completely drained and the tank is dry before adding in the new fuel. Change out the old fuel filter(s) for a new one as well.

Getting Rid of Rust

If you’ve got a steel tank, you may encounter rust, which makes its way into your engine, causes problems over time and isn’t easy to clean. If you’ve got very mild surface-level rust, add acetone and a few cups of smallish rocks. Then, cap off all openings, and go for a drive to get everything moving around. The acetone will coat the rust, and the rocks will knock it off.

Afterward, come back and pour the contents out (again, abide by disposal regulations), and see if you were able to get the rust off. If so, give your tank the soapy water treatment, let it dry completely and then fill it with fuel. If you have rusting that’s more serious, you’re likely fighting a losing battle, so you’d be better off replacing the tank.

To help avoid contamination and rust, pay attention to your fueling source and methods. Don’t let fuel sit for long periods of time, change your fuel filters regularly, and consider alternatives to steel tanks.

Check out all the transfer tank products available on NAPA Online, or trust one of our 17,000 NAPA AutoCare locations for routine maintenance and repairs. For more information on cleaning a fuel transfer tank, chat with a knowledgeable expert at your local NAPA AUTO PARTS store.

Photos courtesy of Blair Lampe.