How to Clean Portable Generator Air Filter? (Correct Way)

generator air filter cleaning

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An air filter allows an internal combustion engine to breathe in the fresh air.

With time, dust and debris accumulate on the air filter obstructing the regular flow of air into the engine.

This hinders the performance of a generator until it stops working.

Therefore, you need to keep your generator’s air filter clean and make it one of the top items on your portable generator maintenance checklist.

But, how do you clean a portable generator air filter?

Remove the foam filter from the air filter housing and wash it thoroughly with liquid soap before letting it air dry. Apply some motor oil on one side of the foam filter and put it back into the housing.

In this post, we’ll talk about the symptoms of a dirty air filter in a generator and the easiest way to clean it.

But first, let’s take a look at the function of a portable generator air filter.

Read More: The easiest way to clean generator carburetor without removing it

What is the Function of a Portable Generator Air Filter?

An air filter of a generator is its lungs that allow it to breathe clean air. It helps remove dust and other debris from the air before sending it into the combustion chamber.

With use, the air filter inside your generator collects dirt that hinders the proper flow of air into the engine. Reduction in the flow of air into the engine of a generator affects its overall performance.

Cleaning a portable generator’s air filter is very easy while replacing one is inexpensive. However, ignoring a dirty air filter can turn into expensive engine repair work quicker than you can think.

How Often to Clean a Portable Generator Air Filter?

The cleaning frequency of a portable generator air filter mainly depends on the use of the machine. The more you use it, the quicker it will collect dust, and the frequent cleaning it will need.

However, a good rule of thumb is to clean the air filter during every scheduled maintenance. Moreover, camping in deserts or other dusty areas will increase the need for air filter cleaning or replacement.

Camping generators will collect dust no matter what, but you can prevent the air filter from getting dirty quickly. Make sure you choose a clean place to run your generator on. Moreover, use a rubber mat or sheet of plywood to prevent dirt intake when boondocking in a desert-like area.

What are the Signs of a Dirty Air Filter?

If a generator’s engine is its heart, the air filter is its lungs. The air filter removes dirt from the air and sends clean air to the engine.

However, the accumulation of dirt in the air filter reduces the amount of air getting to the engine, suffocating the engine. This can result in a wide variety of problems in the long run.

Luckily, symptoms of a dirty air filter are easy to identify once you know what to look for. Here are the most common signs your portable

1. The Air Filter Appears Dirty

The easiest way to tell if your air filter needs a bath or cleaning is by its appearance. Generally, new foam filters will have a single solid color all around them.

Over time, as the unit runs, it accumulates dust and dirt from the air, which settles on one side of the foam, creating a layer. This layer of dust usually has a white-gray look, which is different from the rest of the foam filter.

Therefore, a visual inspection is your first confirmation that you have a dirty or a bad filter. Make sure to inspect the filter during the day under adequate light.

2. Increase Fuel Consumption

A decrease in the number of hours your generator runs on a tank of fuel is a clear indication something is wrong. As the engine starves of oxygen due to a dirty air filter, it burns more fuel to compensate for the power reduction.

As a result, your generator staring burning through more fuel than it would if it received an adequate amount of air. A clean air filter lets the right amount of air into the engine while keeping the fuel consumption to the desired level.

3. Your Generator Misfires or Won’t Start

Your generator will misfire as the balance between the air and fuel mixture is thrown off by a dirty air filter. A low air to fuel ratio in the engine causes it to run rich, forcing the engine to pop.

Moreover, you’ll reach a point where the air filter will become completely clogged, preventing your generator from starting altogether. If you’ve got a generator that is idling rough, sputtering, or won’t start, then the air filter is the first place to check.

4. Unusual Engine Noise

Generally, a well-maintained generator sounds smooth, be it ideal or under load.

As the flow of air is cut short, it makes your generator create unusual sounds due to the starvation of oxygen. The engine will start knocking, revving up and down, increasing vibration, etc.

Any unusual engine sound is a good clue that you have a clogged or bad air filter.

5. Black Smoke from the Exhaust

The reduction of oxygen into the engine prevents fuel from burning properly. The incomplete combustion produces black smoke from the exhaust.

Moreover, due to improper combustion, the unburned fuel from the combustion chamber is sent down the exhaust system which then drips off the exhaust pipe. This unburned fuel sometimes catches fire when it touches the hot exhaust pipe creating a flame from your exhaust pipe.

6. The Smell of Fuel

The incomplete combustion forces the unburned fuel to drain through the exhaust pipe creating a strong smell of gasoline. Though a strong smell of gas can also mean leakage in the fuel system, you can check the exhaust pipe for dripping gas to confirm.

The above are the most common signs of a dirty air filter in a generator. However, cleaning your air filter is the easiest fix for all the symptoms of a dirty filter.

How to Clean a Portable Generator Air Filter?

Fortunately, cleaning or replacing a portable generator’s air filter is very easy and inexpensive. However, be sure to check the manufacturer’s guidelines for your specific generator model, but the steps below will work for most foam air filters.

Here are the steps you need to follow to clean your portable generator air filter.

1. Turn Off the Generator

Before you run any maintenance work on your generator, make sure to turn off the machine, unplug all the appliances, and let it cool down. Generators produce electricity and heat, both of which can harm you.

Now, bring your machine out to a properly lit, well-ventilated place.

2. Locate the Air Filter Housing

Generally, air filters are housed in a closed plastic box in the generator known as air filter housing. On most open-frame models, this housing is located right beside the pull start handle.

For inverter generators, you need to open the service panel to access the filter housing. Unclip the front panel of the housing and bring the filter out.

3. Clean or Replace the Filter

Visually inspect the foam filter to confirm if it is dirty. You can simply blow off the dirt or use a vacuum cleaner to clean it if the dust cover is light.

However, you need to wash it with detergent or a washing agent like Simple Green if the filter looks very dirty. Once you’ve washed it thoroughly, let it air dry out in the sun.

Washing a dirty filter will give it the ability to function properly. But, if the air filter looks worn out or chips of the foam are falling off, then it’s time to replace the filter.

Portable generators foam filters are inexpensive items. Here are a few foam filters you can have a look at.

4. Apply Oil to the Filter

Once the filter is crispy dry, apply some motor oil on the side that faces the inside of the housing. Make sure the oil doesn’t drip off the filter and wipe off the excess with a clean cloth or kitchen towel.

5. Replace the Filter

Put the foam air filter in the correct orientation back into the housing. Close the cover and fasten the clips.


Dirty air filters are common in camping generators as they get used regularly and in places with a lot of dirt and dust. However, cleaning your air filter regularly will prevent generator problems and extend its life.

Make sure to clean it when dirty and replace it if worn out.