How to Start a Generator That Has Been Sitting? Easy Maintenance Guide!

Generators are mostly used in households as a backup power supply, in case of a power outage. Since the usage is often limited to emergencies, chances of a generator not working immediately is pretty high. In that case, you need to know how to start a generator that has been sitting for months or even years.

No need to get panicked if your generator doesn’t start right away. To make the generator up and running again, do a basic check and thoroughly clean the surface. You also need to drain out the old oil and replace it with clean and new fuel. A faulty spark plug or clogged up carburetor or air filter can be the culprit as well.

Keep reading this article to find out more about how to start a generator sitting and other maintenance practices that could help prolong your generator’s lifespan.

How Long Can A Generator Sit Without Use?

There is no precise answer to this question. A generator can be stored for several months without use, however, you need to carry out regular checkups and maintenance procedures. You also need to store it properly, that being covered and safe from dust, moisture, dirt, etc.

How Long Can A Generator Sit Without Use

After acquiring a new generator from a seller or a manufacturer, check the user’s manual or ask the employees. They will advise you on how to carry out maintenance practices on a specific generator model.

To ensure longevity and avoid inconveniences in the near future, you need to be extra careful about the regular maintenance part. This is very important as it will enable the machines to last longer than it’s expected lifespan.

Some of the maintenance recommendations include-

  • If you are using the generator continuously, it should only be for a maximum of 500 hours, especially the standby generators.
  • If you are irregularly using it, run the engine every month and run a proper servicing each year.
  • You should store it in a cool and dry place away from direct contact with moisture or water droplets and dust.
  • Always ensure to drain the used oil and refill the oil tank with the right amounts of fresh fuel every time before use. This will help you avoid rust and contamination in the interior parts of the generator with foreign particles to meet its efficiency and power output levels.
  • A fuel stabilizer is essential to prevent the oil from gumming up on the carburetor.

How To Start A Generator That Has Been Sitting

Generators are usually used as substitutes for the power supply, meaning you may have to store it for a long time. Some owners also use generators in specific circumstances. For example, generators for power bowfishing lights are only used during night fishing. In construction sites generators are used to mix concrete.

When a generator stays stored for long without servicing or frequent maintenance, it will face some challenges while starting for immediate use.

In order to help you understand how to start a generator that has been sitting, below I have gathered some helpful tips that you will need to bring your generator to life and running as usual.

How To Start A Generator That Has Been Sitting

1. Clean the whole generator

The first thing you will need to do is thoroughly clean off dust particles. This will depend on how dirty the generator is. If it is stored in a dust-free area, you will use less time and effort to clean it. Otherwise, use a wet towel or a spray with a degreaser to wash away the dust.

2. Drain off the fuel and replace it with fresh fuel

Most generators will decline to function due to old oil in the fuel tank. When used oil stays in the fuel tank for a long time, will loose the viscosity and the original color will turn to a cloudy appearance. This oil isn’t ideal for a generator to run. So, you need to get rid of that oil and replace it with fresh fuel.

Also, running a generator out of gas can cause the engine not to function as expected.

If you don’t want to waste the oil used only for a few times, instead of letting it stay inside the generator while not in use, you should empty the tank. Then store the oil in a clean container away from direct sunlight and any contaminations. By doing this, it can be freshly available when you need to reuse it.

To avoid the oil from gumming up the carburetor or thickening up into a cloudy appearance, use a fuel stabilizer. This will also help you keep the existing fuel inside the tank for a few months.

3. Replace the oil filter

It is advisable that you also change the old oil filter to a new one because it is not good to use an old filter after fueling the generator with new oil. This fresh oil might not penetrate swiftly through the filter, or it might get contaminated with the old fuel particles, causing inefficiencies in performance.

4. Clean the carburetor and replace the air filter

Cleaning the carburetor is a process that needs extra careful hands since the cleaning process will expect you to remove the fuel line and tank before taking the carburetor out. If you’re doing it yourself, make sure to use a carburetor cleaner.

Air and fuel mix up inside the carburetor before combustion occurs; thus, it is crucial to replace the air filter to have a free flow of clean air inside the carburetor if air circulation is not enough. The size of the filters varies with the type of engine you are currently using, so it is also required that you carefully read the instructions while installing a new one.

5. Check the spark plug

You need to grease the spark plug as it is easy to accumulate rust. This should be practiced more often for better results and should be done carefully by opening the spark plug, pouring some oil in the hole, and replacing the spark plug. For even distribution of oil, withdraw the recoil about four times.

6. Battery built generators

Regularly cleaning the contacts or terminal connections on the battery to get rid of rust can be a significant maintenance measure. Use a wire brush for this case, and if you see no change, you will have to replace it.

What Can Cause A Generator Not To Start?

Generators are standby machines, meaning they can stay for prolonged periods without use. This state of idleness often causes the generator not to start. Here are some possible reasons behind your generator failing to start and what should be done to prevent it:

1. Dead Battery

A malfunctioning battery is one of the most known causes of a generator not starting. It could be due to a loose connection, or the battery needs to be recharged. Always check and ensure your battery connection is tight. We recommend replacing your generator battery after every three years.

What Can Cause A Generator Not To Start

2. Oil Level

Put your generator on even ground and check the oil level. If it is below the recommended level, consider refilling.

3. Choke Lever Position

The choke lever could be in the wrong position. It should be on the closed side when starting your generator then moved to open after the engine has warmed up.

4. Clogged Carburetor

If your generator has been idle for an extended period, chances are the carburetor could be clogged, especially if you didn’t drain it. Try draining the stale fuel and cleaning the main jet using a needle.

5. Out of Fuel

Check your fuel tank and ensure you have enough gas. Refill with fresh gas if need be. If the gas is more than two months old, replace it with new gas. Do not use stale gas.

6. Check the Spark Plug

You will need a spark plug wrench to unplug this. Usually, the spark plug gets dirty and could prevent your generator from starting with time. Use a small knife to clean it. Ensure the electrode is well gapped.


A generator that has not been in use for a prolonged period often develops issues relating to gas or oil. This needs to be addressed before using it again. This article has outlined a step-by-step procedure for starting a generator that has been sitting. You can try diagnosing it with the above-discussed measures. However, there could be a serious technical hitch if it doesn’t work after all. We recommend consulting your technician

Although not directly linked to generator storage but is worth mentioning that you should always take essential safety precautions while using your generator. For instance, you shouldn’t use your generator indoors; keep it in a well-ventilated shed 20-feet away from your house. Always allow your generator to cool down before you refuel it. And lastly, never plug your generator directly into an electrical wall outlet.

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