Inline Fuel Filters for Gas Engines and Diesel Burners

Dirty fuel wrecks carburetors and burner fuel pumps, and both repairs cost fifty times what a filter does. This collection covers inline fuel filters for the gas engine side of your machine and fuel oil filters for the diesel burner side of hot water units. Grab your fuel line size before you order, or call 301-519-9274 and we will match the filter to your machine. Looking for water filtration ahead of the pump instead? That lives in our water filters collection.

Two Fuel Systems, Two Kinds of Inline Filter

Cold water machines have one fuel system, the gas line feeding the engine. Hot water machines have two, because the burner drinks diesel or kerosene from its own tank. Each system clogs in its own way. Gas lines pick up grit during dusty refueling and grow ethanol varnish during storage. Diesel tanks collect water from condensation, and water is what kills burner fuel pumps and clogs burner nozzles. Filter both sides and the whole rig stays out of the shop.

Sizing the Engine-Side Filter

Match the filter to the inside diameter of your fuel line, not to the engine size. Most GX-pattern engines run 1/4 inch line, and many import engines run 5/16 inch. These small engines are gravity fed, so there is no fuel pump pushing gas through a half-plugged filter. An undersized or clogged filter starves the carb and the engine surges or dies under load. If your line is cracked or gummy, replace it at the same time. We stock bulk fuel line for $2.13 and a 4.5 x 235 fuel line for $15.88, both on the shelf now.

Metal Disposable or Clear Plastic

Clear plastic housings let you see contamination at a glance, so they earn their keep on machines that sit between seasons. Metal disposable filters shrug off heat, vibration, and the occasional boot strike on a crowded skid. Neither type is rebuildable. When one darkens or the engine starts surging, cut it out, press a new one into the line, and clamp both ends.

Burner-Side Fuel Oil Filters

Burner filters are canister assemblies with replaceable elements rather than throwaway inline cartridges. The Mitco 264 is the standard 3/8 inch FPT fuel oil filter on many hot water skids. The Racor 140R adds water separation, which matters if your diesel tank rides outdoors on a trailer through Maryland humidity. Our 1/4 inch FPT small assembly takes a replacement cartridge, so you swap the element and keep the housing.

Filter Lookup by Machine and Line Size

From the Field

The tell is in what we sell most. Burner service calls in fall almost always trace back to summer diesel sitting in a vented tank, breathing humid air, and dropping water to the bottom where the pickup tube lives. A ten minute filter swap in September beats a no-heat call in November. On the gas side, the pattern is contractors refueling from a can that rode in a dusty truck bed all week. One gritty refuel puts more junk in a carb bowl than a year of clean running. A five dollar inline filter between the tank and the carb catches it. Cheap insurance is an overused phrase at this counter, and it is still the right one.

Related Collections

• All fuel filters
• Burner parts and burner nozzles
• Fuel pumps
• Fuel tank accessories
• Engine parts and Honda parts
• Carburetor components
• Water filters and strainers for the pump inlet
• Pick up same day at our Gaithersburg pressure washer store

Frequently Asked Questions

Does my pressure washer engine really need an inline fuel filter?

Most small engines ship with only a small screen in the tank. An inline filter adds a second barrier that catches rust, grit, and ethanol varnish before the carburetor. It costs a few dollars and installs in minutes, and a carb cleaning costs far more.

What size inline fuel filter fits my machine?

Measure the inside diameter of the fuel line. Most GX-pattern engines use 1/4 inch line and many import engines use 5/16 inch. Match the filter barbs to that size so the connections seal without splitting the hose.

Which is better, a metal or clear plastic fuel filter?

Clear plastic shows you the dirt, which helps on machines that sit for months. Metal handles heat and knocks better on a working skid. Both are disposable, so replace rather than clean them.

How often should inline fuel filters be replaced?

Once a season on working machines, or sooner if the element looks dark or the engine surges under load. Burner canister elements should be swapped every fall before heating season.

Why does a diesel burner need a fuel and water separator?

Diesel tanks breathe moist air and condense water inside, and water corrodes the burner fuel pump and misfires the flame. A separator like the Racor 140R traps water below the element so only clean fuel reaches the burner.

Can a clogged fuel filter cause my burner to smoke or cut out?

Yes. A starved burner runs lean, sputters, soots the coil, and eventually locks out. If the flame is weak and the fuel filter has not been changed in a year, change it first before chasing electrodes or nozzles.

Do these filters clean the water going to my pump?

No. These handle gasoline and fuel oil only. For sediment in your supply water, use an inlet filter from our water filters collection.