How to Dissolve Sludge in a Gas Tank?

Is sludge in your gas tank a big deal? Yes, sludge is a big deal because it contains contaminants and microbes that will damage your fuel system.

While the sludge stays anchored at the bottom when the gas tank is full, once the fuel level depletes, the contaminants will damage your fuel system.

This will surely affect the overall performance of your vehicle. You’ll also need to replace fuel system components if the sludge clogs your supply line.

The good news is there are ways to dissolve the sludge and preserve the overall performance of your vehicle.

Want to know how to dissolve sludge in a gas tank?

Keep reading!

How to Dissolve Sludge Using Lye?

The following are steps to dissolve sludge in a gas tank using lye.

Step One – Buy Lye

If your car has been sitting for quite some time without the engine running or getting started, then chances are there may be sludge in your gas tank.

gas tank of old car

In fact, if you use a flashlight to look inside the gas tank, you’ll discover the sides are probably lined with a black gummy substance.

You’ll also notice a very strong odor emanating from the gas tank. If you start your car, this gunk can find its way to your carburetor and cause damage.

The good news is you can dissolve the sludge using lye. Before getting started, visit your local store or Amazon and look for lye.

Regarded as safe for use with foods, it’s great for dissolving sludge as well as making pretzels, bar soaps, biodiesel, and more. We recommend that you buy 2 or 3 cans.

The reason why we recommend lye to dissolve sludge in your gas tank is that it’s proven to dissolve oils and fats. You can also use it to clean grease from grease traps, and exhaust hoods.

Step Two – Remove the Gas Tank from Your Car

Before dissolving the sludge in your gas tank, you need to remove it from your car. Start by putting ramps under the rear wheels, then jack up the rear of your car.

Avoid using jack stands as they will block the forward movement of the gas tank’s deck. The deck is the board on which the tank sits. Do not use cinder blocks for ramps.

Next, remove the metal plate and the spare tire. The plate covers the wood supporting the spare tire.

Once you do so, you should see 4 nuts and bolts holding the tank to the wooden deck. Remove the nuts and bolts, then disconnect the fuel line.

Drain the gas tank. You can use a 3/16 wrench for the drain plug on the left rear corner of your gas tank.

There are four carriage bolts attaching the deck to the chassis. Remove the bolts. In some cases, the bolts may turn in the wood.

If this happens, you’ll have to cut the nuts and bolts off. We recommend using a hacksaw or die grinder and then using a drift to push the bolts through the deck.

Slide the tank and deck forward. The gas tank is light so you can set it on your chest and then slide out from under the car.

Step Three – Drain the Gas Tank

There are several methods of draining your gas tank. In the first method, we will use a simple siphon hand pump.

Fuel gauge empty gas tank

Before draining the fuel, gather the following items:

  • Fuel storage can
  • Clean cloth or rag
  • Long thin screwdriver

Start by opening up the fuel filler door, removing the fuel cap then feeding the siphon pump tubing into the fuel tank.

We recommend that you feed the tubing in small increments. Since it’s flexible, the tubing will kink.

Some vehicles will have a small metal flap or door preventing the tubing from being fed into the gas tank. If this is the case with your car, then use the long thin screwdriver to push the flap or door open. Proceed to feed the siphon pump tubing into the gas tank.

Take the other end of the tubing and feed it to your fuel storage tank. Begin pumping until you see the fuel flowing through the tubing.

Continue pumping until all the fuel is completely drained. This process may take time depending on the amount of fuel in your gas tank.

Once the gas tank is fully drained, you can store or dispose of the fuel properly.

In method two, you’ll need the following items:

  • Safety glasses
  • Jack and jack stands
  • Hand tools
  • Drain pan
  • Tire chocks or wood blocks
  • Shop rag

Set the parking brake, then place the chocks or wood blocks under the tires. This will prevent the vehicle from rolling.

In this process, you don’t need to remove the fuel tank. Simply raise one of the rear wheels using a jack or jack stand.

Once raised, locate the drain plug. Make sure to put on your safety glasses before sliding under the car.

Place a drain pan underneath the plug, then start loosening the drain plug. Remove the drain plug by hand, then allow the fuel to drain into the pan until the gas tank is empty.

Take caution that the fuel may spill out once you remove the drain plug. It’s important to have rags or towels to wipe out any spills. After the fuel tank is completely drained, replace the drain plug.

Step Four – Dissolve the Sludge

As aforementioned, we recommend the use of lye to dissolve the sludge in your gas tank. Lye is a caustic substance, sodium hydroxide to break down and dissolve the sludge build-up in your gas tank.

It’s very cost-effective. Not only does it get the job done, but you can reuse it over and over. Add the lye to the water, never the reverse.

We recommend one pound of lye per 3 to 5 gallons of water. When you add lye to water, it will create a thermal reaction, which may cause the mixture to boil up. If you’re not careful, it may splash on you.

So, we recommend that you have safety glasses, clothing, work boots, and gloves. The warmer the lye solution is, the faster it dissolves the sludge. It’s important to keep another container filled with fresh water close by to rinse the tank.

As the lye solution reacts with the sludge and starts dissolving it, the mixture will become black as coffee. Once the solution dissolves every bit of the sludge, its efficacy will get diminished.

If you think disposing of the lye solution is hard for you, we recommend that you contact your local hazardous waste disposal company.

Simply search for the location nearest you, and they will dispose of the lye solution containing the dissolved sludge.

Place a couple of layers of household plastic over the fill hole, and gas cap then slosh the lye solution. This will ensure that the lye solution dissolves all the sludge in the gas tank.

Remove the fuel cap and drain the solution. Repeat the sloshing every half an hour or until finished. To properly dissolve the sludge, it may take all day.

Take your garden hose and rinse the gas tank. Rinse over and over, then allow the gas tank to dry. You can speed up the drying process by using a hair dryer or an air hose on your compressor.

Take your flashlight and look inside the gas tank. Is the inside as clean as a nickel?

Or are there traces of the sludge on the surfaces?

If the interior of the fuel tank is clean, good job. Now, you can reattach the fuel tank once it’s completely dry.

Can I Use a Solution of Baking Soda and Vinegar to Dissolve the Sludge?

Yes, you can use a solution of baking soda and vinegar to dissolve the sludge in your gas tank. Once you remove the gas tank (as mentioned in Step Two), spray water into the tank.

Use the water hoses and pressure attachment. Make sure that you spray the inside walls well. Drain or siphon the water from the gas tank.

baking soda and vinegar

Mix a cup of baking soda and 2 cups of white vinegar in the gas tank. Fill the tank three-fourths of the way with water.

This will create a cleaning solution that will break down and dissolve the sludge. Allow the solution to sit in the gas tank overnight. This will ensure the complete removal of the sludge.

Drain the solution from the gas tank and rinse the inside several times. This will remove any traces of the cleaning solution.

Now fill the tank and rinse all its sides. Do so at least four times. This will ensure the gas tank is free of the cleaning solution’s residue.

Take a hair dryer and dry the gas tank. Make sure there is no moisture or dampness inside the tank as this will result in rust or the build-up of sludge.

After the gas tank is completely dry, reattach the fuel hoses and gas tank to your vehicle. Now you can add fuel and allow the vehicle to run.

Can I Clean My Gas Tank Without Removing it?

Yes, you can clean your fuel tank and dissolve the sludge without removing the tank. Here are the steps to complete this process.

Step One – Disconnect Fuel Lines

Just like in the previous method, you need to disconnect the fuel tank lines. Make sure you do not damage the connections.

If you’re not sure, we recommend reading the owner’s manual on the right way to disconnect the fuel tank lines.

Step Two – Drain the Gas Tank

Next, drain the fuel tank. There are two ways of doing this, use a siphon hand pump or the drain plug.

If draining the fuel by the drain plug, simply jack your car on its rear. This will allow the fuel to drain faster and better from the gas tank.

After draining all the fuel, prepare a mixture of any kind of degreaser with hot water. We recommend any commercial degreaser you can find at your local store.

Add the mixture to the fuel tank and allow it to sit for at least 24 hours. If the gas tank still smells of gasoline after 24 hours, repeat the process.

Step Three – Wash Your Fuel Tank

Using a high-pressure water flow, wash your gas tank. This will help to get rid of all the debris and sludge.

Try to point your water nozzle at different angles. This will allow you to make a full wash and clean all sides of the gas tank. While washing your gas tank, make sure you’re wearing safety goggles, clothing, work boots, and gloves.

Step Four – Add a Cleaning Solution

After degreasing your gas tank, it’s time to add a cleaning solution. The active ingredient in the cleaning solution will dissolve the sludge.

We also recommend the use of any commercial cleaning solution. After applying the cleaning solution, wash off the sludge.

Allow the cleaning solution to sit for a couple of hours – at least 6 hours. After that, you should be able to remove the sludge and any rust with ease.

Step Five – Rinse Your Gas Tank

Rinse your gas tank with water to remove traces of the cleaning solution and sludge. Spray the tank with water until there is no smell of gasoline.

Step Six – Dry Your Gas Tank

After cleaning your gas tank with water, leave it in the fresh air for it to dry. Alternatively, you can use a hair dryer to completely dry the gas tank.

Make sure no traces of moisture are present in the fuel tank. Drying takes 24 to 48 hours.

If you don’t allow your gas tank to completely dry, the water can cause problems. For example, you’ll start experiencing problems with changes in speed or acceleration.

Once the gas tank is completely dry, reconnect the hose and connection of the fuel tank in places. Close the drain port and add some fuel before running your vehicle.

What Is the Best Cleaning Solution for Dissolving Sludge?

The best cleaning solution that will dissolve sludge from your fuel tank is Star Tron Fuel System Cleaner. Formulated to treat up to a 500-gallon tank, Star Tron is a concentrated formula that removes sludge from gasoline and diesel fuel tanks.

To dissolve sludge in your fuel tank, all you need is to add 1 fl. Oz for every 4 gallons of fuel.

Allow the mixture to sit in your gas tank for at least 24 hours. The cleaning solution will disperse sludge and hardened deposits that clog filters.

To effectively clean and remove the sludge, perform two treatments. Once you do so, not only will you dissolve the sludge but you will no longer clog your fuel filters.

How to Know If Your Vehicle’s Fuel System Needs Cleaning

The following are signs that your vehicle’s fuel system needs cleaning:

If you try to accelerate your car or are driving up a hill and your vehicle’s engine turns off, it means your fuel pump is not supplying a steady stream of fuel to your engine.

If your vehicle’s temperature rises up and then your vehicle stalls, it’s a sign that your fuel system needs cleaning. When this happens, your fuel pump will start to deteriorate, and you may need to replace it.

If you accelerate fast and your vehicle sputters at high speeds, there is something wrong with your fuel system. This happens because your fuel system is struggling to supply fuel to the engine.

If you notice your vehicle consuming more gas than usual, then your fuel system needs cleaning. A fuel pump that’s about to fail means more fuel will flow into the engine than necessary

If your vehicle’s engine won’t start and there is nothing wrong with your battery or ignition, it’s a sign your fuel system needs cleaning.

Final Thoughts

Cleaning your gas tank by dissolving the sludge is necessary to prevent damage to your fuel system components.

Sludge and other contaminants damage fuel systems and compromise your vehicle’s performance.

Now that you know how to dissolve sludge from your vehicle’s gas tank, you can save money on repairs and the replacement of fuel system components. Not only that. Your vehicle will not experience performance issues.

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