How To Start A Generator That Has Been Sitting

Ready to bring your generator back to life after it has been sitting idle for a while? You’ve come to the right place! In this article, we will walk you through the step-by-step process of starting a generator that has been sitting, ensuring you have a reliable power source whenever you need it. Whether it’s due to seasonal storage or infrequent use, we understand that getting your generator up and running can be a daunting task. But fear not! Follow our guide, and you’ll have your generator humming along in no time.


Before you can start a generator that has been sitting for a while, there are a few important steps you need to take to ensure its optimal performance. Here’s what you need to do:

Gather necessary tools and materials

To perform the necessary maintenance on your generator, you’ll need a few tools and materials. Make sure you have items such as a wrench, screwdriver, cleaning brushes, fresh fuel, oil, fuel filter, and air filter ready before you start.

Check the generator’s condition

Inspect the overall condition of your generator. Look for any signs of physical damage or wear and tear that may require immediate attention. Ensure that all the components are securely in place and that there are no loose or missing parts.

Inspect the fuel and oil levels

Check the fuel and oil levels in your generator. If the levels are low, you’ll need to top them up before starting the generator. It’s important to use the correct type and grade of fuel and oil as specified by the manufacturer.

Ensure proper ventilation

Generators produce exhaust fumes that can be harmful if not properly ventilated. Make sure that the area in which you’re operating the generator has adequate ventilation to prevent the buildup of carbon monoxide. Never operate a generator indoors or in enclosed spaces.

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Fuel System

The fuel system of your generator plays a crucial role in its functioning. Here are the steps you need to follow to ensure the fuel system is in good shape:

Drain old fuel

If the generator has been sitting for an extended period, the fuel inside may have become stale or contaminated. Drain out the old fuel to prevent any issues during start-up. Dispose of the old fuel properly according to local regulations.

Replace fuel filter

After draining the old fuel, it’s essential to replace the fuel filter. Over time, the fuel filter can become clogged with debris, affecting the generator’s performance. Install a new fuel filter to ensure a clean fuel supply.

Refill with fresh fuel

Once the old fuel has been drained and the fuel filter replaced, refill the generator with fresh fuel. Be sure to use the recommended fuel type and grade specified by the manufacturer. This will ensure optimal combustion and prevent fuel-related issues.

Purge air from the fuel system

After refilling with fresh fuel, it’s important to purge any air that may have entered the fuel system. This can be done by following the manufacturer’s instructions, which usually involve operating a priming pump or fuel valve to remove air pockets.

Oil System

The oil system of your generator needs to be properly maintained for optimal performance. Here’s what you need to do:

Check oil quality and level

Inspect the oil quality and level in your generator. If the oil appears dirty or has a milky appearance, it may need to be changed. Additionally, ensure that the oil level is within the recommended range as indicated by the dipstick.

Change the oil if necessary

If the oil quality is poor or the level is low, it’s crucial to change the oil. Refer to the generator’s manual for specific instructions on how to drain the old oil and refill with fresh oil. Regular oil changes help prolong the life of your generator’s engine.

Clean or replace oil filter

While changing the oil, it’s a good idea to clean or replace the oil filter as well. The oil filter helps remove impurities and contaminants from the oil, ensuring that it flows smoothly through the engine. Follow the manufacturer’s guidelines for cleaning or replacing the oil filter.


The battery plays a vital role in starting your generator. Here’s what you need to do to ensure it’s in good condition:

Inspect battery terminals

Check the battery terminals for any signs of corrosion or loose connections. Corroded terminals can prevent the battery from supplying power to the generator, so it’s important to clean them properly.

Clean corroded terminals

If you notice corrosion on the battery terminals, clean them using a battery terminal cleaner or a mixture of baking soda and water. Gently scrub the terminals and connections to remove any buildup. Wipe them dry before reassembly.

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Charge or replace the battery

If the battery is low on charge or unable to hold a charge, you may need to charge it using an appropriate battery charger. Alternatively, if the battery is old or damaged and cannot be restored, it’s best to replace it with a new one for reliable generator start-ups.

Air Filter

The air filter in your generator prevents dust, dirt, and debris from entering the engine. It’s essential to keep it in good condition. Here’s what you need to do:

Inspect the air filter

Check the air filter for any signs of dirt, clogging, or damage. A clogged air filter can restrict airflow to the engine, leading to decreased performance and potential engine damage. Inspect it carefully to determine whether it needs cleaning or replacement.

Clean or replace the air filter

If the air filter is visibly dirty or clogged, it needs to be cleaned or replaced. Cleaning the filter involves gently tapping it to remove loose debris or using compressed air to blow out the dust. If the filter is damaged or excessively dirty, it’s best to replace it with a new one.

Spark Plug

The spark plug is responsible for igniting the fuel-air mixture in the combustion chamber. Here’s what you need to do to ensure it’s in good condition:

Remove and inspect the spark plug

Carefully remove the spark plug using a spark plug wrench. Inspect the electrode and the white insulator for signs of wear, fouling, or damage. If the electrode is worn down or covered in black carbon deposits, it’s likely due for cleaning or replacement.

Clean or replace the spark plug

If the spark plug appears dirty or worn, it’s best to clean it using a wire brush, making sure to remove any carbon deposits. However, if the spark plug is damaged or excessively worn, it’s recommended to replace it with a new one to ensure a strong spark for ignition.

Ignition System

The ignition system of your generator needs to be in proper working order to start and run smoothly. Here’s what you need to do:

Check ignition switch and controls

Inspect the ignition switch and other controls for any visible damage or signs of wear. Ensure that they operate smoothly and that all connections are secure. Faulty ignition switches or controls can prevent the generator from starting or running reliably.

Inspect spark plug wire connections

Check the spark plug wire connections to ensure that they are secure and free from corrosion. Loose or corroded connections can disrupt the flow of electricity and result in a weak or no spark, leading to starting issues. Clean or tighten the connections as necessary.

Test the ignition coil

The ignition coil is responsible for generating the high voltage required to create a spark. Perform a visual inspection of the ignition coil for any signs of damage or wear. If you suspect a faulty ignition coil, it’s best to consult a professional technician for testing and potential replacement.

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Cooling System

The cooling system of your generator helps regulate the engine temperature and prevent overheating. Here’s what you need to do:

Inspect radiator or coolant level

If your generator has a liquid cooling system, make sure to inspect the radiator or coolant reservoir for proper coolant level. Ensure that the coolant is within the recommended range and that there are no visible leaks or cracks in the system.

Clean or replace the radiator

Over time, the radiator can accumulate dust, debris, and other contaminants that can hinder its cooling efficiency. Clean the radiator using compressed air or a soft brush to remove any buildup. If the radiator is damaged or severely corroded, it may need to be replaced.

Check cooling fan operation

Ensure that the cooling fan is functioning correctly. Check for any obstructions or damage that may impede its rotation. A faulty cooling fan can lead to overheating and potential engine damage. If you suspect an issue with the cooling fan, consult a professional for inspection or repair.

Start-up Procedure

Once you’ve completed the necessary maintenance steps, follow this start-up procedure to ensure a successful start:

Set the generator to ‘Run’

Before starting the generator, make sure the switch or control is set to the ‘Run’ position. This allows the generator to operate once started.

Turn off all electrical loads

Before starting the generator, ensure that all electrical loads or appliances connected to it are turned off. This prevents any potential damage to the generator or the connected devices during start-up.

Choke the engine if necessary

If your generator has a choke, engage it according to the manufacturer’s instructions. The choke helps enrich the fuel-air mixture during start-up, especially in colder temperatures, facilitating easier ignition.

Pull the starter cord or use starter button

To start the generator, either pull the starter cord briskly or press the electric starter button (if equipped). Follow the manufacturer’s instructions for your specific generator model.

Allow the generator to stabilize

After starting the generator, allow it to run for a few minutes to stabilize. This lets the engine warm up and ensures that it reaches its optimal operating temperature before connecting any electrical loads.

Maintenance Tips

To keep your generator in good working condition, it’s important to follow these maintenance tips:

Regularly start and run the generator

Even if you don’t need to use your generator regularly, it’s advisable to start and run it for a few minutes every month. This helps lubricate the internal components and prevents the build-up of stale fuel.

Keep the fuel fresh

To avoid fuel-related issues, it’s crucial to keep the fuel in your generator fresh. Use stabilized fuel, rotate your fuel storage to prevent it from getting too old, and drain the fuel tank if the generator will be idle for an extended period.

Change the oil as recommended

Regular oil changes are essential for maintaining the longevity of your generator’s engine. Refer to the manufacturer’s recommendations for the recommended oil change intervals and follow them accordingly.

Clean or replace filters periodically

Inspect and clean or replace the air filter, fuel filter, and oil filter at regular intervals. This helps ensure that your generator receives a clean and adequate supply of air, fuel, and oil, maximizing its performance and lifespan.

By following these comprehensive steps and incorporating regular maintenance practices, you’ll be able to start your generator that has been sitting and keep it running smoothly for years to come. Remember safety precautions and always refer to the manufacturer’s instructions for specific maintenance procedures relating to your generator model. Happy generating!

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Albert Stein

Starting this site about today's portable power options was an easy choice as it's one of my passions. Tech changes constantly so you need to make an informed decision before purchasing the wrong products. -Thank you.-

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