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How to Get Water Out of a Lawnmower Gas Tank, step by step

Even when you check the weather forecast or rain radar regularly, it is always possible that you unexpectedly get into a shower. When you quickly get inside, you leave your lawnmower outside, and it will get wet. Usually, this is not a problem, but when water or moisture somehow get into the fuel tank, it is a different story.

It is always suggested to store your lawnmower in a nice safe shelter, so your machine is safe from environmental hazards. Keeping it out in rainy weather or a damp shed may cause it to quit working at some time. If you have forgotten to store your lawnmower after using it, it is exposed to some rainy weather, and it does not start. It can be an indication that water has seeped into the gas tank. To fix this, you have to remove all the water from it.

How to get the water out of a lawnmower gas tank, step by step:

  • Step 1: Diagnose if there is Water in Your Lawnmower
  • Step 2: Disconnect the spark plug
  • Step 3: Siphon the diluted gas
  • Step 4: Dry the tank
  • Step 5: Drain the oil
  • Step 6: Empty the carburetor bowl
  • Step 7: Dispose of all the diluted oil
  • Step 8: Refill the tank
  • Step 9: Use a fuel additive to combat moisture in your tank
(CC BY-SA 2.0) by djuggler

Once you have realized that there has been water contamination to your lawnmower’s gas tank, there is no need to panic. The problem is not difficult to fix. Make sure you do not ignore the problem, as it can cause severe damage to your engine. Long term damage to the lawnmower may include corrosion in the tank, fuel lines, and the carburetor.

Water in the lawnmower’s gas tank can be due to it being left out in the open when it was raining, and some rainwater seeped into the gas tank. Another possibility is that your lawnmower is stored in such a warm place during daytime and is cold at night that it makes a partial vacuum that sucks moist air into your tank. There it condenses and settles down at the bottom of the tank.

Although lawnmowers are made waterproof, there is always the chance for accidents like these to take place, particularly when the lawnmower is older.


Get the water out of the lawnmower gas tank in 9 easy steps.

● Step 1: How to diagnose if there is water in your Lawnmower.

The first thing to do is to confirm that your lawnmower has water contamination in its gas tank. If your lawnmower has one (or more) of the following problems after being exposed to rain or a damp environment, there is a high chance it is caused by water in your gas tank:

– Hard Starting

Water is denser than gas, sinks at the bottom of the gas tank, and most of the lawnmowers’ models draw gas from the tank’s bottom. Hence, when you start the lawnmower, the gas tank’s water will go into the carburetor before fuel and cause problems.

– Poor Performance

When the quantity of water in the fuel is not very significant, the engine will start fine. But the water can result in poor performance and will not accelerate like it should when throttled.

– Continuously starting and sputtering

When the water in the fuel tank is in small amounts, the engine will start smoothly, but your mower may suddenly sputter or stall or completely stop running. Often it may yet start again, but the same thing may happen again.

– Fuel System Damage

If you notice any problems in the performance caused by the accumulated water in the lawnmower’s fuel system, check your engine as soon as possible. If you are too late, it may inflict significant damage to your engine. You can protect your lawnmower from any damages such as corrosion or rust over time.

– Smoke coming from the engine

Sometimes you may also notice an unusual amount of smoke coming out from the engine, which can be due to poor combustion in the piston chamber.

● Step 2: Disconnect the spark plug.

The first thing you must do is to remove the spark plug for safety purposes.

● Step 3: Siphon the diluted gas.

The second step is to siphon the diluted gas out of the lawnmower. For this purpose, insert the siphon tube of a hand-pump into the gas tank of the lawnmower. Insert the drain tube of the pump in the container where you will collect the diluted gas. Now pump the device and extract all the gas from the tank.

● Step 4: Dry the tank

Although you have extracted the gas, there may still be a little water attached to the walls inside the tank. So, carefully dry the tank with a dry piece of cloth, or you can also use compressed gas or by spraying it with a WD-40.

● Step 5: Drain the oil.

Now the next step is to drain the oil. Tilt the mower by propping up the front of the mower on blocks. And pun a collecting pan under the machine’s drain plug, which is located at the underside of the mower.

Unscrew the plug with a wrench, and wait for all the oil to drain out into the pan. If there is no drain plug, lift the carburetor from the side on which the air filter or the carburetor is located and pour the oil out from the oil fill hole.

● Step 6: Empty the carburetor bowl

Now empty the carburetor bowl. It is a metal cylinder that is usually located on the side of the mower. Wipe thoroughly all around the bowl with a dampened rag with carburetor cleaner to not let the dirt from falling once it is removed.

Also, place a rag under the bowl to catch the liquid. There will be at least one set bolt present. If you find a second offset bolt, then it is a drain plug.

If there is no drain plug, then unscrew the bolt and pour out the carburetor bowl’s contents.

● Step 7: Dispose of all the diluted oil.

Collect all the diluted gas and the oil and dump them at the local hazardous waste recycling facility.

● Step 8: Refill the tank

Now reconnect the fuel line and refill the tank with fresh gasoline and engine oil.

● Step 9: Use a fuel additive to combat moisture in your tank

If you live in an area where moisture is a problem using a fuel additive could be the right solution. An example of such a fuel additive is HEET. It is specially made to remove water from your gas tank.

This method may be more costly, but if it means you can avoid damage, your lawnmower will be avoiding it is more than worth it.

Note: Make sure that there is more gas than water in your tank. Else the fuel additive will not work. Check the fuel additive manual for more information.

Related Questions:

1) How did the water get into my gas tank when I never left it out in the rain?

Although your lawnmower has never been left out in the rain or may not have been in contact with water, water still enters the gas tank by condensation.

This phenomenon occurs in the winters, usually when you leave your lawnmower in a damp and humid place.

For this issue, you should tightly close the opening of your tank so that no water can seep in. Also, try not to store your lawnmower in such places and try to buy a plastic cover for your lawnmower.

2) Why is my lawnmower oil milky?

If the oil color from your lawnmower is ‘whitish milky,’ then it is contaminated with water. The oil with greenish milky color is because of the presence of antifreeze in it. If the addition of water to the oil is due to condensation of water in the engine, then the milky white color should disappear when you warm the landowner.

3) Are lawn mowers waterproof?

A lawnmower can not be completely waterproof. However, water can still be used to clean your land mowers. Landowners are designed to tolerate a little bit of rain on the lawnmower’s engine.

After the rain, turn on the mower and heat it for a few minutes. The engine’s heat will evaporate the water and clear the moisture, which will protect the motor from the rust.

Final Remarks:

Although your lawnmower may be waterproof, water can still enter your lawnmower’s gas tank (by the causes mentioned above). The best way is to drain out the water contaminated fuel and refill it with the new one. The alternate yet slightly more expensive method is to use the fuel additives. Both of these methods are fine, and you should choose which one fills your needs.

So the best way to avoid this inconvenience is to keep your lawnmower at a dry place in winters. You can also buy a plastic cover to protect it and be sure to close the opening of the tank tightly. Taking serious precautions is better than facing severe damages to your machine or following a rigorous step to fix it.

The Impact of Water in a Gas Tank on a Mower

One of the serious problems that can impact the operation of your mower, potentially causing severe performance problems, is the presence of water in the gas tank.

The consequences of this issue can be long-term, causing lasting damage to your mower’s fuel system. The elements most susceptible to the damage include the tank itself, the carburetor, and the fuel lines. An important factor here is corrosion, which is often triggered by the presence of water.

• Recognizing Water Contamination in Your Mower’s Gas Tank

Water contamination is not always immediately obvious, but there are some symptoms to look out for. The general performance of your mower can give away the presence of water in the gas tank. One notable symptom is hard starting.

If your mower requires an excessive number of attempts to start and tends to stop and resume operation unexpectedly, water contamination in the gas tank may be the culprit.

Poor performance in running mode is another evident symptom that should alert you to possible water contamination in the mower’s gas tank.

• Addressing and Solving Water Contamination Issues

If you have recognized the symptoms of water contamination in your mower’s gas tank, it’s crucial to act promptly. The first step to rectify the issue is checking the gas tank for visible water globules. Upon ascertaining the presence of water, the next step is to drain the contaminated fuel from the tank.

To fully rid the mower of the contaminated fuel, you should also dry out the tank. This can be done using a small rag, compressed air, or even a little WD-40. The latter isn’t just handy for lubrication but also acts as a water displacer.

But the process doesn’t end there. After successfully drying out the tank, the fuel line must be reconnected, and the tank should be refilled with fresh, uncontaminated gasoline.

• Dealing with Severe Water Contamination

In cases of extreme water contamination, it may mean that the tank and carburetor are too contaminated. If that is the situation, it’s necessary to remove and thoroughly clean these parts. As part of this process, you should also check for any possible moisture present in the combustion chamber. Additionally, adding some engine oil to the piston chamber is a good measure against future occurrences.

If you aren’t experienced with engine repair, it’s highly recommended to seek professional help. Mowers are complex machinery, and mishaps during repair can further complicate or worsen the existing issues.

• Preventing Future Water Contamination

Prevention, as always, is better than cure. To prevent future cases of water contamination, you should consider several preventative measures. Firstly, it’s critical to store your mower in a protected environment.

This will assist to minimize the risk of water exposure. If placing the mower in a shielded environment isn’t possible, consider purchasing a plastic cover. This serves as an additional layer of protection, shielding the mower from elements.

More information on the best care and maintenance practices for mowers can be found at PennState Extension, a non-commercial educational website. This will help you to take all necessary precautions to prevent water and other contaminants from getting into your mower’s fuel system.

Remember that consistent care and maintenance for your mower can save you from high-cost repairs down the line. Always be vigilant about storing and using your mower to maximize its performance and lifespan. A correctly functioning, well-maintained mower allows a much smoother lawn care experience.

• Water Entry in Lawnmower’s Gas Tank Through Condensation

It is not commonly known but quite common for water to enter lawnmowers’ gas tanks. This ingress is usually a result of condensation occurring inside lawnmower storage areas when they are damp or noticeably humid.

The temperature differences in such environments lead to condensation, which can facilitate the seepage of water into the gas tank. Therefore, storing your lawnmower in such places will not be conducive.

• Securely Closing the Gas Tank Opening

To prevent the ingress of water, make a conscious effort to close the gas tank’s opening securely. Sometimes, we may overlook this detail, leaving the tank susceptible to water seepage. It’s a simple but very effective way of safeguarding the mower against water damage.

• Dealing with Rainfall

Rainfall may seem harmless, but it can affect your lawnmower. While it can tolerate minimal rain on the engine, prolonged exposure could lead to rust. Therefore, always ensure you promptly dry the mower after it gets wet in rainfall. This practice helps keep rust and, in the long run, extend its durability.

• Identifying Water Contamination Through Oil Changes

Monitoring the oil in a lawnmower is a great way to detect water contamination. Usually, oil changes to a milky appearance if there’s water contamination. The National Ag Safety Database provides useful information on this and other safety issues.

• What Does a Greenish Color of Oil Suggest?

A peculiar color change you should look out for is green when you notice a greenish color in the oil, that typically indicates the presence of antifreeze a coolant used to prevent overheating. Antifreeze should stay within the cooling system, so its presence in the oil is indeed a cause for concern.

• Draining Water-Contaminated Fuel

Upon finding water contamination in the fuel, one effective solution would be to drain the contaminated fuel completely from the gas tank. After draining, re-fill the tank with new, uncontaminated fuel.

This practice aids in curbing the negative impact water-contaminated fuel may have on the functioning of the mower.

• Using Fuel Additives to Remove Water

You could also use fuel additives to remove water from your lawnmower’s gas tank. Available in most auto parts stores, these specially designed additives aim to separate the water from the gas.

Consequently, this allows for easy water removal, thereby preventing possible damage to your lawn mower’s system.

• Storage Tips during Winter Months

Winter months are notorious for their heightened humidity levels. During this time, endeavor to store your lawnmower in dry, ideally indoor, places. For added protection, consider using a plastic cover to shield it from any water droplets in the air.

• Neglect of Water in Gas Tank and its Repercussions

Ignoring the issue of water in your lawnmower’s gas tank can come with daunting consequences. Over time, it can instigate severe damage to various parts of the mower, which include the tank itself, the fuel lines, and the carburetor, primarily through corrosion.

Stay vigilant about this and prevent annoying repairs and replacements.

• Final Thoughts

Care & maintenance of your lawnmower goes beyond regular servicing and oil changes. Keeping it dry, storing it properly, and paying attention to changes in the oil’s appearance are key. Keep these points in mind to extend your equipment’s life and ensure its optimal performance.

The Ethanol Effect: Water in Your Lawnmower’s Gas Tank

As a veteran gardener and lawnmower enthusiast, I have often come across a recurring problem faced by many – water in the gasoline tank of your lawnmower. Unbeknownst to many, a prime participant in water contamination in lawnmower gas tanks is ethanol-containing gasoline.

During alcohol fermentation, ethanol is produced, which is then mixed with gasoline to create a cleaner burning fuel source. But there’s a dark side to this sustainable practice – it readily absorbs water, leading to potential harm to your lawnmower.

I would strongly recommend using ethanol-free gas for your lawnmower, which is available at specialized retail outlets.

• Uncovered Gas Cap: An Overlooked Culprit

Another usual suspect when it comes to water in lawnmower fuel tanks is a missing or loose gas cap. Extended periods without a cap allow moisture from the atmosphere to seep in.

As an experienced operator, I cannot stress enough the importance of adequately securing the lawnmower and storage cap, as a simple oversight can cause unnecessary frustrations and equipment damage.

• Recognizing Signs of Water Contamination

Knowledge is the key to prevention. Understanding the symptoms of water contamination can save you time, money, and headaches. The most characteristic signs include difficulty in starting the lawnmower or unusual spluttering before it eventually cuts out.

Furthermore, poor engine performance characterized by a constant shift in revving speed can also be an indicator of water in the tank.

Learn more about the signs and symptoms of water in your gas tank.

• Remedial Action: Removing or Dispersing the Water

Upon detecting water in the tank, swift action is critical. There are two options available to rectify this issue. The first involves removing the fuel tank, cleaning it, and refilling it with fresh gas. I recommend this method, as it effectively eliminates all traces of water.

An alternative solution involves the use of isopropyl (rubbing) alcohol. Adding this to the fuel tank can help evaporate the existing water. However, remember to exercise caution, as not all lawnmower engines are designed to burn it.

• Important Precautions: Disposal and Damage Prevention

Right from disposing of the old gas and water to using alcohol in your tank – remember to practice caution at every step. Used gas and water should be disposed of following your local guidelines. You can check the Environmental Protection Agency’s guidelines on safe disposal of gasoline.

Adding isopropyl alcohol can be quite abrasive for some engines. Therefore, make sure to familiarize yourself with your lawnmower’s specifications before doing so. As a seasoned expert in this field, I advise that checking the user manual should be your first step.

• Maintaining Functionality: Evict the Water

A word of caution – water not only affects the performance of your lawnmower but also leads to potential damage through corrosion.

Therefore, at the first signs of water in the fuel tank, swift remediation is crucial. Keep in mind that preserving the functionality of the lawnmower isn’t a one-time effort; it’s a combination of regular check-ups, early problem detection, and appropriate steps for correction.

For garden lovers like myself who pride themselves on a well-maintained lawn, these pointers could make the difference between a smooth-functioning lawnmower and a frustratingly unproductive one.

• The Impact of Water Contamination on Your Lawnmower’s Gas Tank

Water contamination in your lawnmower’s gas tank can lead to serious issues such as hard starting, poor performance, sputtering, and, in some cases, fuel system damage. Consequently, it’s crucial to tackle this problem promptly and effectively.

• Initial Precautions

Before delving into fixing the water contamination issue, an important safety measure is disconnecting the spark plug. This reduces the risk of accidental ignition or injury as you work on the device.

• Draining Off the Diluted Gas

For the actual draining process, everyday tools like a hand pump can be used to siphon the diluted gas out of the lawnmower. Environmentally safe disposal of polluted gas is critical.

Many local hazardous waste recycling facilities accept diluted gasoline. You can find more information about this on EPA’s hazardous waste web page.

• Drying the Interior

After siphoning the gas, it’s paramount to thoroughly dry the tank. A dry cloth, compressed gas, or even something like WD-40 could be used for the drying process.

• Draining the Oil

This becomes an essential step, especially in cases where the water contamination is severe. To drain the oil from the lawnmower, you can tilt it and remove the drain plug or lift the carburetor to pour out the oil. Milky or whitish oil is typically an indication of water contamination.

• The Importance of Cleaning the Carburetor

Additionally, emptying the carburetor bowl is another important step. Various components in the carburetor may possess set bolts or drain plugs, and undoing these will help pour out the contents directly.

• Filling the Tank with Fresh Gasoline

Upon completely drying and emptying the tank, it must be filled with fresh gasoline and engine oil.

• The Use of Fuel Additives

An effective moisture-combating trick that has worked for me is using fuel additives like HEET. Not only does it remove any existing water content, but it also prevents future water contamination.

• The Source of the Water Contamination

The issue of water contamination might seem irrelevant if you’ve never left your lawnmower in the rain. But the reality is that condensation can be a significant culprit for water entering the lawnmower’s gas tank.

• The Importance of Proper Storage

For this reason, ensuring that your lawnmower is parked in a dry place during the winter is crucial. While lawnmowers are designed to tolerate some rain, they are not completely waterproof. Thus, taking precautions to prevent water infiltration is essential to their longevity.

• The Pursuit of a Water-Free Fuel System

The importance of completely removing water from the fuel system cannot be overstressed. Thoroughly doing so not only prevents damage but also ensures the smooth and efficient functioning of the lawnmower.

In conclusion, the effects of water contamination in a lawnmower’s fuel system can be severe. Therefore, proactive steps should be taken to prevent it, and reactive measures should be implemented promptly once it occurs.

Remember, the longevity of your lawnmower is significantly dependent on its upkeep and care.

The Importance of Fuel Stabilizers in Lawnmower Fuel Storage

Fuel stabilizers play a crucial role in maintaining the quality of your lawnmower’s fuel during extended storage periods. Over time, fuel breakdown may occur, causing major engine problems. Adding fuel stabilizers is a preventive measure that acts against the degradation of fuel. It’s an effective way of deterring water contamination, especially during longer storage periods.

• Securing the Gas Cap

The gas cap is a small, yet mighty component of your lawnmower’s fuel storage. This part meets the tank opening and locks into place, simply acting as a cover. But more than that, it prevents water from infiltrating into the gas tank.

Properly securing the gas cap is one safeguard against water intrusion. A loosely fitted or missing gas cap may expose your tank’s contents to the elements and allow entrance of water.

• Water Damage to the Fuel System

Water-contaminated fuel can spell disaster for your lawnmower’s fuel system. Water intruding into the system can lead to a clogged fuel filter, fuel lines, and carburetors – a recipe for poor engine performance.

Essentially, it’s about avoiding contamination at all costs. A clean, efficient, and long-performing fuel system is the antidote to any lawn mower mechanical nightmare.

• How Water Enters Gas Tank

Storage conditions are a major factor that can lead to water entering the gas tank. When a lawnmower is stored in damp or humid locations, condensation can form. This condensation may seep into the gas tank, leading to contaminated fuel.

The U.S. Department of Energy highlights the adverse effects of water on fuel systems (more info here).

• Identifying Water Infiltration Signs

Hard starting, poor engine performance, and excess smoke with a fuel smell are signs of water in the gas tank. A properly functioning lawnmower shouldn’t exhibit such signs. When your lawnmower’s behavior deviates from the norm, it’s a clear sign to check for possible water contamination in your gas tank.

• Removing Water from the Gas Tank

In the event water infiltrates your lawnmower’s fuel system, it is crucial to act fast. First, ensure safety by disconnecting the spark plug. Then, proceed with removing the gas tank, fuel lines, and carburetor.

Drain the contaminated fuel and allow the gas tank to dry completely. As for the carburetor and fuel lines, clean the carburetor bowl and fuel lines thoroughly to ensure no residue of contamination remains.

• Safe Disposal of Contaminated Fuel

After draining the contaminated fuel, it is crucial to dispose of it safely. Never dump it down the drain or into the soil. This is hazardous and can harm the environment. A local hazardous waste disposal facility can help with the proper disposal of such waste.

• Refilling Gas Tank and Using Fuel Additive

Post water removal from the gas tank, refilling should be done with fresh gasoline. A fuel additive that combats moisture is recommended. This acts as a final shield against any residual moisture that may still exist in the system.

• Prevention is Key: Storage and Maintenance

Preventive measures cannot be overstated when it comes to maintaining the health and longevity of your lawnmower. Storing the lawnmower in a dry location and performing regular maintenance are steps towards preventing water contamination in the fuel tank in the first place.

Remember, your lawnmower is a significant investment. A chalked out prevention and maintenance protocol will save you from potential expenses towards repairs or new purchases, and ensure your lawnmower serves you well through the years.