How Often Should You Run Your Generator? 20-Minute Maintenance Test

Ken Jorgustin
37 minutes ago
6 min read

How often should you run your generator? And how long should you run it for maintenance?

Here’s the practical answer…

Quick answer: Run a portable generator at least twice a year, but preferably every 1 to 3 months. Let it run for about 20 minutes, long enough to reach normal operating temperature, and plug in a moderate load so you know it is actually producing power. Before starting, check the oil and fuel. After the test run, disconnect the load before shutting it down.

I try to run my generators about every 3 months or thereabouts. Monthly is even better, especially before storm season or winter. Sometimes I forget too. But running it several times a year is a whole lot better than discovering a problem when the lights are already out.

Important Safety Reminder: Generator Outdoors Only

Before we get into maintenance, this is worth saying up front.

Never run a portable generator in a garage, basement, shed, porch, carport, or any enclosed or partly enclosed space. Even with doors open, carbon monoxide can build up quickly.

Run the generator outdoors, at least 20 feet away from doors, windows, and vents. Point the exhaust away from the house. Also, make sure you have working carbon monoxide detectors in the home.

This is not just for actual power outages. It also applies during a quick maintenance test.

Verify Your Portable Generator Works, BEFORE You Ever Need It!

Every once in a while, it’s a good idea to run your generator!

This is a reminder to do your due diligence. Wheel your portable generator out of the garage or wherever it is stored, set it up safely outdoors, and start it up. Let it run for awhile. Plug something into it so you know that it’s actually outputting power!

Start your generators!

Generator maintenance, at a minimum, involves simply running your generator from time to time. Why?

To keep its internal parts lubricated with oil
To charge the battery, if it has one
To help prevent carburetor issues
To put it under load and verify power output
To make sure the generator actually works before an emergency

How Often To Run Your Generator

I try to run my generators every 3 months. That’s a practical schedule for me.

Even better? Once a month.

Minimum? At least twice a year.

Here’s how I would look at it:

If you live where winter storms, hurricanes, ice storms, or frequent outages are a concern, I would lean closer to monthly testing. You want to find out about a dead battery, old fuel, low oil, or no power output while you still have options.

How Long To Run Your Generator For Maintenance

I let my portable generators run for about 20 minutes.

That’s long enough for the engine to reach normal operating temperature. This is important. Don’t just run it for a few minutes and shut it down.

A very short run is not as useful. When a generator is started and then shut down while still cold, moisture can remain inside the engine. Water is created during the combustion process. When the engine gets warm, most of that moisture can evaporate before the engine cools down.

So let it run until it’s actually hot.

Run The Generator Under Load

Don’t assume that just because the engine is running, the generator is producing usable electricity.

It probably is. But why guess?

Plug in a reasonable load and verify that the outlets are working. Something more than just a little light bulb. A hair dryer, small heater, shop vac, or similar load can work, depending on the size of your generator.

Important: Disconnect the load before starting the generator, and disconnect the load again before shutting it down. Load it only while it’s running.

20-Minute Generator Maintenance Test Checklist

Here’s a simple routine:

Move the generator outdoors before starting.
Keep it well away from doors, windows, and vents.
Check the oil level.
Check the fuel condition.
Make sure loads are disconnected before starting.
Start the generator and let it warm up.
Plug in a moderate load.
Confirm the outlets are producing power.
Let it run for about 20 minutes.
Disconnect the load before shutdown.
Shut off the fuel valve and let it run dry if you are storing it.

That’s not complicated. But it may save you from a dead generator when you really need it.

Check The Oil Before You Start The Generator

This is a primary reason why people inadvertently destroy their generators.

If you run the generator out of oil, it may destroy the engine. Some generators have automatic low-oil shutoffs. But don’t count on that, especially with some less expensive models.

Check the oil before every start.

Simple. Fast. Important.

Fuel Tips For A Generator That Sits Unused

Fuel is one of the biggest problems with portable generators because they often sit unused for long periods of time.

Gasoline does not age well, especially in small-engine fuel systems. Over time it can cause varnish, gum, and clogged carburetor jets. If you have gasoline that has been sitting around for many months, it may eventually cause starting problems or poor engine operation.

This is particularly true with portable generators because they may sit idle until the next storm, outage, or emergency.

Run It Dry

When you’re just about done running the generator, shut off the fuel line and let it run dry until the generator stalls out.

This consumes the fuel from the carburetor so it doesn’t sit there and potentially gum up over time. If you forget, this may become a problem later when the generator won’t start.

Remember to shut off the fuel valve while the generator is still running, then let the generator run itself out from fuel starvation. It may take a minute or two.

Since the fuel shutoff valve isolates the gas tank from the carburetor, once the generator uses up that remaining fuel, the delivery system and carburetor are cleared of fuel. Nothing left sitting in there to gum up the works.

Fuel Additive / Stabilizer

A way to increase fuel shelf life is to use gasoline fuel stabilizer. It can help extend fuel life and inhibit fuel from gumming up inside the carburetor while the generator sits idle.

Use Ethanol-Free Gas If You Can

When able to do so, use ethanol-free gasoline for your generator. Highly recommended.

This will greatly help reduce the chance of gumming up the works. Search online for stations near you that sell ethanol-free gas.

I use ethanol-free gasoline for all of my small engines here at the homestead. It tends to “stay good” for a lot longer. So, if you find a place near you that sells it, that’s where I would fill your gas cans for generator fuel.

Electric Start Generator? Keep The Battery Charged

Does your generator have a battery for electric start?

If so, running it once in awhile may help keep the battery charged. But don’t rely on occasional running alone. It’s also a good idea to put that battery on a trickle charger or maintainer once in awhile.

I’ve lost a battery because of this. Whoops.

This is my favorite little 12-volt battery trickle charger and maintainer:

Carbon Monoxide Detector

If you use a portable generator, you should have working carbon monoxide detectors in your home.

This is especially important during winter outages when doors and windows are closed and people may be running generators, wood stoves, propane heaters, or other fuel-burning equipment.

A generator belongs outside. A CO detector belongs inside.

Heavy-Duty Extension Cord For Your Generator

The right extension cord matters. Don’t run a generator with a light-duty indoor cord that was never designed for the load.

Use a properly rated, heavy-duty outdoor extension cord matched to the wattage and distance involved.

Extended Fuel Tank For Generator

This isn’t necessary for a basic maintenance test, but it can be useful during a longer outage.

An extended run generator fuel system allows you to supplement your generator’s factory fuel capacity with a stable vacuum-powered fuel supply. Popular with the highly rated Honda generators such as the EU1000i, EU2000i, and EU2200i.

If You’re Shopping For A Quiet Portable Generator

Most people searching this topic probably already own a generator. But if you’re looking for a quiet, reliable portable inverter generator, the Honda EU2200i is a popular choice.

How often should I start my generator?

Start and run your generator every 1 to 3 months if possible. Monthly is best, every 90 days is a practical routine, and twice a year is the minimum I would be comfortable with.

How long should I run my generator for maintenance?

Run it for about 20 minutes, or long enough to reach normal operating temperature. A very short run is not as useful because the engine may not get hot enough to evaporate moisture.

Should I run my generator under load?

Yes. Plug in a moderate load so you know the generator is actually producing power. Do not assume everything is fine just because the engine starts.

Is it okay to run a generator with old gas?

Old gas can cause starting and carburetor problems, especially in small engines that sit unused. Use fresh fuel when practical, consider fuel stabilizer, and use ethanol-free gasoline when you can get it.

Should I run the generator dry after testing?

For storage, shutting off the fuel valve and letting the generator run until it stalls can help clear fuel from the carburetor. That reduces the chance of gum and varnish causing problems later.

Can I run my generator in the garage with the door open?

No. A portable generator should not be run in a garage, basement, shed, porch, carport, or any enclosed or partly enclosed space. Use it outdoors, at least 20 feet away from doors, windows, and vents, with the exhaust pointed away from the house.