12 Steps On How to Drain Gas from Generator

Generators are essential appliances for any homeowner and business. From outages during hurricanes and ice storms to weekly power failures, they are your lifeline in tough times. They, like any mechanical device, require routine maintenance. On such occasions is when you need to know where and how to drain fuel.

If you are going to store your generator for an extended period, it’s important to empty all gasoline.

Gasoline has a shelf life between three to six months, depending on temperature and sunlight exposure. Over time, the residue left in your generator tank will begin to break down, causing corrosion and clogging to your tank and any hoses attached to it.

So this article will show you how to safely drain gas from your generator to avoid some of the most common problems and be back up and running in no time.

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Materials and Tools Needed


  • Long funnel

How to Drain Gas from Generator

  • A clean rag
  • Pliers

How to Drain Gas from Generator

  • Screwdriver
  • A gas collecting container

A Step-By-Step Instructions on How to Drain Gas from Generator

1. Turn off the Power Switch and Pull the Plug

It never hurts to double-check and switch off everything before starting any work. So first, make sure that all power switches are turned off – both at your home and at the outlet.

Also, pull out all the plugs as an extra precautionary measure. Ensure there is no possible way for current to flow through your system before attempting anything else.

2. Open the Gas Tank Cap

To allow airflow in your generator’s gas tank, twist the cap open. This is critical because airflow reduces gas spills and leaks caused by pressure variations when refilling or draining your gas tank.

3. Find the Gas Valve Switch

Most gas-powered generators feature an access point for draining remaining fuel from their tanks. While these access points may look different from unit to unit, they usually take the form of a small valve-like port or switch located near the generator’s exhaust vent.

So, when you’ve located the switch, flip it upwards until the plastic cover is pushed through. If you can’t find yours, consult your owner’s manual.

4.  Remove the Maintenance Cover Plate

You’ll need to remove the cover panel to access the fuel lines with some models.

Maintenance covers are usually located beneath your generator, and you can remove them with a screwdriver or hex key tool. Therefore, remove any screws or bolts holding down your cover plate and set them aside for later use.

5. Push the Gasoline Valve Out of the Plate

Once you’ve removed your generator cover, push out your fuel valve. It should come right out with only slight pressure. Double-check to ensure your fuel valve is off to avoid fuel leaks, which could be a fire hazard.

6.  Take the Aluminum Clip off the Fuel Line

To remove gas from your generator, you’ll need to drain it out of its fuel line. There should be an aluminum clip holding the fuel valves together. If you can’t pull it off with your hands alone, gently push it back with your flathead screwdriver or pliers.

However, it would be best if you did not detach the tube from the gas tank; otherwise, the gas would spill all over the place.

7. Place the Fuel Valve Tube into an Oil Drain Pan

Set up an oil drain pan to catch any gas that drips out. Then, in your container, place your gasoline valve tube. Make sure your collection vessel is below ground level and big enough (approximately 18.9–37.9 L) to hold all of the gas from your generator.

8. Turn on the Fuel Valve

Turn on your fuel valve so that gas can begin to flow out of your generator into your transfer container.

Depending on your tank’s size, it may take up to five minutes for the gas to drain. Check periodically, and when the tank is empty, turn off your fuel valve and reconnect the fuel lines.

9. Replace the Cover

After you’ve drained the gas from your generator’s tank, make sure you replace the cover. Screw it back into place to ensure no rain or other outdoor elements can reach your gas.

10. Locate the Carburetor to Drain Gas Residue

The carburetor is usually located near the bottom or below your generator’s fuel tank. It often has a screw at the base for opening and closing, so finding it should be easy. If you’re unsure which part is the carburetor, consult your generator’s instruction manual for assistance.

11. Under the Carburetor, Place a Collection Container

Using a screwdriver, loosen the screw holding down your carburetor drain plug but not altogether remove it. Turn it to the left until gas begins to flow into your collecting container (note that only a tiny amount of gas will come out).

12. Retighten the Screw to Close the Carburetor

Once you’ve successfully removed all of your gas, retighten the screw to close up the carburetor. Be careful not to over-tighten as this could damage it.

Now you are ready to store your generator for as long as needed and re-fuel when it is time to start up again.

Frequently Asked Questions about How to Drain Gas from Generator

Here are some frequently asked questions about how to drain gas from generators to get you started on the process.

1. Do I need to drain gas from a generator?

You should always drain the gas out of your generator after using it. Gas evaporates, and air builds up in the carburetor over time when stored for long periods leading to leakage or formation of bubbles which causes damage to internal parts.

2. Can you siphon gas from a generator?

Siphoning gas is an easy way to get rid of your old, unwanted gasoline. It involves transferring gas using gravity.

To use a siphon, place one end of the clear hose in your fuel tank and position your mouth over the other end of the hose, allowing you to suck outgas. The force of your breath should cause fuel to flow through.

3. How long should you leave gas in a generator?

How to Drain Gas from GeneratorGasoline can last for about six months in a generator. You can prolong its shelf life by treating it with a stabilizer additive, which keeps it fresh for a long and provides better protection against water contamination. Stabilizers contain chemicals such as ethanol that extend gasoline’s shelf life up to 12-18 months.

4. Should I leave gas in my portable generator?

How to Drain Gas from GeneratorGasoline can be left in the tank if the generator is stored for a limited time. Leaving it for long periods can cause damage to your generator’s carburetor and fuel system, so it should be drained when reserving longer than several weeks.

5. What happens if you overfill a generator with gas?

Overfilling your generator with gas can cause a dangerous build-up of fumes inside of it. You can’t mix air in when there’s too much gas required for burning.

Furthermore, overfilling can result in an explosion because there isn’t enough room for those gasses to expand into when the fuel is ignited.

6. How do you get old gas out of a gas tank?

It’s all about siphoning it out. It would be best to have a long tube and something at both ends to let air through while keeping liquid in its place.

At one end, seal off part of your tube. Then run it through your car’s gas tank so that once in there, no more air can come through—but the liquid will leak out and flow down into another container below.

7. Does a generator use more gas with more things plugged in?

Generators use gas based on their load, which means they burn more fuel when more things are plugged in. You should make sure your generator is operating at its optimal load; if not, it may become damaged and stop working correctly.

8. Can you use old gas in a generator?

Old gas might be contaminated with rust, dust, and other impurities. Using contaminated gas can not only affect your generator’s performance but also affect how well it works in an emergency. Drain out the older gas and replace it with new fuel for better safety and reliability.

9. Should you use premium gas in a generator?

Premium gas is for maximizing engine power and fuel efficiency. Thus, it’s best used in high-performance generators because it has fewer hydrocarbons than lower grades and higher-octane rating. Most generators can use regular-grade fuel because they run at low speeds.

10. Can you leave a generator running unattended?

No. Never leave a generator running unattended or outside where it could be exposed to rain, hail, or snow. Running a generator out requires you to use a professional-grade exhaust stack, and in some cases, that means installing one yourself.

For example, if you are burning natural gas in your generator, an EPA-approved carbon monoxide monitor must be installed inside your home. If left running for more than 4 hours without proper venting and monitoring equipment, dangerous levels of CO can build up indoors.

11. Where do you store a generator when not in use?

The generator should be kept in an area not exposed to direct sunlight or inclement weather conditions. Such exposure will shorten its life and affect performance. Also, please keep it away from areas where rainwater could seep into its fuel tank, which can cause rusting of your unit.

12. How do you winterize a gas generator?

First, drain all of the fuel out of your generator and store it indoors in a safe place.

Also, if you’re storing your generator for longer than three months, change all of its oil since it can get gummed up in there after sitting unused for an extended period.

13. Is it right to use a stabilizer on a generator?

A stabilizer is an antioxidant used to protect gasoline from becoming stale. If the generator is not in use for more than six months at a time, you’ll need to add a stabilizer. If you’re able to use it often, it’s not necessary.

14. How do I check the gas level in my generator?

Generators typically have gas caps in their engines that you can twist open for checking. Some are vented, and you’ll need to unscrew them, but most gas caps will be located at or near the base of your machine.

15. Can you overfill a generator with oil?

If you overfill your generator with oil, it will overflow, causing a mess and posing a severe safety risk. Your engine block and cylinder head should only have enough oil to cover the low areas. Allow room for expansion since gasoline expands as it heats up.

16. Why is my generator consuming too much oil?

Valves in your fuel tank may be slightly damaged and allow small amounts of gas to leak out without properly burning the engine. Another possible reason is that your generator isn’t getting enough air when running at certain speeds or loads.

17. How many hours can a generator run on 5 gallons of gas?

Most gas-powered generators can run for about 8 hours on 5 gallons of gas. If you have only a small generator, it might last even longer. These figures will differ depending on which brand and model you use.

Final Thoughts

Knowing when and how to drain gas from your generator is essential if you want it to run at its peak efficiency and last a long time. Additionally, it will help save you money by letting you use more of your fuel and keep environmental waste down.

As you’ve seen in our guide, you don’t need any special tools or a lot of time to drain the gas.

While it may require extra attention and diligence, learning how to drain gas from your generator is a crucial skill if you want your engine to function at its best and survive a long time.


About Steve Stuart

Steve Stuart is an electrical engineer who developed interest on generators during his school years. After school, he became a generator enthusiast. This is after encountering power supply problems at the area of residence where he lived. Power would be on and off and so food would go bad and the room heater would go off especially during winter. After trying the different generator brands for several years, Steve now provides information on the available brands and products in the market today. Based on his experience, he gives the do’s and the don’ts when it comes to generator use.

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