While we’re being fleeced each time we fill the car with a full tank of gas, not many of us stop to consider the quality of the fuel we’re pumping into our vehicles. Engines are sensitive even to the smallest particles of debris, dirt, or contaminants that can easily wreak havoc if it weren’t for fuel filters. They make sure to remove all impurities before the gas or diesel reaches the engine.
What Are Fuel Filters?
These are one of the most important but also most overlooked vehicle components. They are an essential part of the fuel delivery system and protect parts like fuel pumps and nozzles by removing dirt, particles, and moisture from the fuel.
Different designs have been in use for more or less than a century but have evolved to withstand the high-pressure environments that make up a modern engine. Materials and filtering elements differ, from plastics to metals in housings and cellulose and micro-glass in the filters themselves.
Depending on the quality and type of the fuel, the car fuel filters on the market are rated for at least 30,000 miles, but some have been known to go as far as 100 thousand miles and still work flawlessly. Either way, these are some of the least expensive parts to replace and are easy to find.
Cleansing fuels from impurities is their main purpose. It can be dirt, soot, sand, water collecting in the gas tank, or flaking metal particles. Any of these will damage various engine parts (fuel pumps and injectors are the first to go), leading to premature corrosion and wear. In addition, they aid performance by supplying clean fuel for optimal combustion.
Canister vs. Cartridge Filters
Fuel filters can take on different shapes and sizes and are distinguished by the media that rid the fuel of contaminants. Canister filters are some of the most widespread, consisting of an outer canister made of plastic or metal, and a filtering media housed inside.
Similar in design are cartridge filters. These lack the outer shell, with the assembly mounted onto a mating surface on the vehicle. The second type is easier on the environment since the inner cartridge is all that’s replaced.
Fuel Type – Gas or Diesel
This is the main distinction between filters. You’ll either need a gasoline or diesel one. Diesel engines often have a primary filter fitted on the vacuum side of the fuel pump that rids the diesel of larger impurities and debris, whereas a secondary filter fits on the pressure side and cleans out smaller particles and remnants that have come through.
Diesel, by default, contains more contaminants since it involves less refining. Gasoline is cleaner to start with, and a gasoline engine will need only one fuel filtering device, often in smaller dimensions.
This is the inner membrane that captures unwanted particles, as well as any water. The filtering media is often pleated, increasing its surface area and efficiency. It can consist of cellulose and resins, and these provide optimal fuel flow with fewer restrictions. Filters made of micro glass, essentially synthetic glass microfibers, are generally smaller in size, often more restrictive, and usually found in diesel engines.
Where Exactly Is the Fuel Filter on My Car?
Filters have different locations on different cars. Generally, there are three basic types. Those that are fitted to the chassis or frame at the rear of the vehicle and near the fuel tank, those located in the engine bay, and those that form part of the fuel tank itself.
On-chassis filters will often be installed with a mounting bracket and have an inlet and outlet valve at either end. They’re easy to remove, and replacing takes a few minutes.
Filters in the engine bay are more common in diesel engines and some older gas engines. Specifically for diesel, there can be a primary filter between the engine and the fuel tank, and a second one near the firewall.
Lastly, in-tank filters are an integral part of the fuel tank, are commonly coupled with the fuel pump, and are the hardest to replace. You’ll find these more common in modern vehicles.
Signs That the Filter Needs Replacing
General wear and tear will affect car fuel filters like any other car part. Over time, it will lose its ability to function and eventually get clogged. In extreme cases, this isn’t handled on time. The filter’s efficiency drops and it impacts the flow of fuel and ultimately how the engine performs. There’ll be loss of power, strain on the engine internals, and even overheating. But before advanced damage to filters sets in, a few telltale signs will inform you it’s time for a replacement:
- Check Engine Sign – Clogged filters lead to reduced fuel pressure, and something sensors and the ECU won’t hesitate to inform you. While the sign can mean many things, a simple diagnostic scan can pinpoint the problem. Often this will display fueling issues, and the filter is at fault.
- Loss of Power – With the engine starved of the needed fuel (especially at higher RPMs), a faulty fuel filter often means a loss of power. This can be felt on steeper inclines, during harder acceleration, and when towing. When the filter is severely clogged, the vehicle will be hard to start, and if it eventually does, the vehicle will stall soon after.
- Rough Idling – The tacho needle jumping all over the place is a sure sign of rough idling. There’ll be pronounced vibrations, with the engine not getting enough fuel.
- Misfires – While this can mean a range of issues (failed spark plugs and damaged wiring or coils), misfires will happen when the car fuel filter is nearing its expiry date. A sure sign is a distinct judder, particularly when the engine is more stressed than usual. Inconsistent fuel supply and a clogged filter are often the main cause.
Another issue is damage to the fuel pump as it works harder to supply the optimal amount of fuel, and this along with related problems of malfunctioning injectors can incur expensive repair costs down the road.
What to Look for in Replacement Fuel Filters
Obviously, you’ll need one that is compatible with the fuel type and engine requirements. Diesel models also remove water and are quite different from those that cleanse gasoline. Parts makers make this easier for you as they list the vehicle and engine type it is compatible with. They also take into consideration the size and location.
What’s more important is to get fuel filters rated for the correct fuel flow and this depends on the filtering medium. Another factor is efficiency, listed as a micron rating. The lower the number the more efficient the part will be in removing finer particles.
Lastly, get a something from a respected brand. It will ensure that it performs as it should and last for the specified period.