Tips  for Maintaining Small Engine Fuel Filters for Lawn Equipment

Purpose for a Small Engine Fuel Filter:

A lawnmower or small engine fuel filter's job is to prevent dirt, dust and debris from entering the combustion chamber of the engine. It filters impurities of various sizes from the fuel before it enters the carburetor. If the filter gets clogged it will lead to a variety of issues with the power

and performance of your equipment. Maintaining the fuel filter in your lawn mower is an important part of ongoing maintenance.

You will likely encounter issues with your lawnmower. This can be something as simple as an annoying sputter when you try to start the mower, difficulty getting it started, or it can cause the mower to idle unevenly. More serious issues include a lack of power when you are mowing, or the lawnmower won’t start at all.

Types of Fuel Filters:

There are three main types of small engine fuel filters.
1. In-line Disk filters – Small inline disks which contain a filter screen. There are two versions. Red versions have 150-micron screens and are used for gravity fed fuel systems (no fuel pump). The white versions have 75-micron screens and are used for systems with fuel pumps.

2.  In-line Paper Cone Filters – plastic conical in-line filters with an internal paper or felt filter. These are translucent directional filters with an arrow indicating the fuel flow direction. Installing in the proper direction allows debris to be captured on the outside of the paper filter visible through the translucent casing. This facilitates knowing when to replace.

There are a wide variety of shapes, sizes, and specs of this fuel filter type with specific flow rates and micron filtering. These are not universal between all small engine models and brands.Type the part number, generally printed on the filter, into the website for a correct part match.

3. In-tank Fuel Filters – Mostly for 2-cycle engines on trimmers, blowers, and chainsaws. These are small cylindrical filters that fit on the end of the fuel hose inserted directly into the fuel tank.These generally have a higher micron rating so as not to impede the oil in the fuel mixture leading to engine burnout.

Other Small Engine Fuel Filters: 
Specialty Fuel Filters – There are a wide variety of specialty fuel filters for various engines. These can be built directly into a carburetor or into a fuel line. If you do not see one of the three versions mentioned above, you should check your owner’s manual for what type of filter is

Micron Rating Explained:
Micron rating refers to the size of the smallest particles a filter will keep from passing through the fuel line. You may assume that smaller is better, but this is not always the case. Too much filtering may prevent gravity fed engines from getting fuel or 2-cycle engine from getting lubricating oil. Too little filtering may cause other engines to clog or foul early. Follow the owner’s manual to determine what is required. Generally small engine fuel filters are rated from 10 to 150 microns.

What are the signs of a Dirty or Clogged Fuel Filter?
If you haven’t changed your filter at regular intervals, you might notice some odd engine behavior. There are quite a few issues a bad fuel filter can cause.

1. Engine Starting - A clogged fuel filter can starve your engine of fuel causing it to crank longer and struggle to start. You might also hear the engine sputtering when you turn the

2. Idling and Stalling - When operating at low speeds, a clogged fuel filter will cause your equipment to stutter and stall. The bounce of the idling might become more intense.

3. Misfiring - A clogged fuel filter can cause uneven distribution of fuel and create low fuel
pressure in the engine. This will lead to engine misfire.

4. Poor Performance - The speed and handling of the machine seems significantly worse,
especially at high speeds or under load. Sputtering and engine surge may occur.

5. Damaged Fuel Pump – a loud straining sound as it struggles to send fuel to the engine.This may have been caused by a damaged or failed fuel filter which could lead to debris in the engine and more serious problems.

When to Change a Fuel Filter?
All small engine manufacturers recommend changing the fuel filter annually or after about 200 hours of use. If you notice problems related to the fuel system you should inspect the filter and change it earlier if necessary. Pay attention to the warning signs and keep up with the maintenance.

Can You Clean a Small Engine Fuel Filter?
Generally, the answer is no. Small engine filters are small, sealed, and not designed to be reused. They are inexpensive and readily available at or other retailers.

Replacing and Maintaining a Fuel Filter:
Replacing a fuel filter is quite easy. Make sure your equipment is in a safe space away from fire or flame. Use gloves or a cloth to handle the filter. Shut the fuel valve off or drain the fuel tank for in-tank systems. Remove the clips on the fuel line, if there are any, and insert the new filter into the fuel line. Pay attention to the fuel flow direction for directional fuel filters.

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