The fuel we use for our vehicles isn’t as clean as it should be. It contains contaminants that can be harmful if they find their way into your engine. For that reason, car manufacturers place a fuel filter in every vehicle they produce. The location of the filter depends on several factors, but I’ll get to that part later on. First, let’s discuss what exactly it is that fuel filters do and why they’re so important.
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What’s A Fuel Filter?
Fuel filters are straightforward devices installed in the fuel system, and their purpose is to prevent contaminants from getting to the engine. Generally, they’re made of either plastic or metal, and they contain a filtration element. As gas goes from the gas tank to the engine, it passes through the filter first, where it’s cleaned and made ready to use by the engine.
These devices have existed as long as internal combustion engines have. Earlier models were small plastic cans, which were suitable for the engines of those times. This mainly occurs because fuel passed through filters under low pressure, so the device didn’t need to be durable.
Nowadays, however, fuel filters are different in design. This is because many vehicles incorporate direct-injected engines, which require the filter to withstand the high pressure in the fuel system. That being said, modern filters are much stronger and are made of higher-quality materials.
My Mazda MX5 has an MX5 fuel filter that’s more robust and is shielded against excessive pressure with the help of special relief valves. Having said that, you must choose a filter that’s suitable for your type of vehicle, including model, make, and year to ensure a proper fit.
However, keep in mind that the features on my MX5 fuel filter are only necessary because the filter itself is fitted outside the fuel tank, i.e., on the fuel line or the engine bay. These fuel filters are known as inline filters, and they have to be capable of withstanding internal and external factors.
On the other hand, filters that are mounted inside the fuel tank have to withstand different fuel blends. Different types of filters are designed to put up with different factors based on their location.
Location of Fuel Filters
As briefly aforementioned, the fuel filter can be mounted almost anywhere between the engine and the fuel pump. Most vehicles have them mounted inside the fuel tank, but some fuel pump assemblies have the filter inside.
In older vehicles, fuel filters were generally connected to the fuel line under the vehicle’s body. Some have it in the engine bay, allowing it to remove contaminants before it gets to the engine. That being said, the location will depend on a few factors, including the type of fuel system, car model, make, and year.
Finding the filter is easy – just follow the fuel line until you see it. If you can’t find it on the fuel line, it’s probably inside the fuel tank.
How Do Fuel Filters Work?
Fuel filters consist of an inlet and outlet, as well as a filter medial. The fuel pump uses high pressure to push fuel along the fuel line, causing it to move through the filter media with force. The filtration material is porous and based on the size of the pores; fuel passes while the contaminants remain behind.
Like those found in diesel engines, some fuel filters feature a mechanism that helps remove water from the fuel. In other words, these filters feature a bowl at the bottom where the water separated from the fuel gathers. These filters feature a water sensor that gives you a warning when the water needs to be drained from the bowl with the help of drain valves.
Types of Fuel Filters
Fuel filters are categorized as canister or cartridge, spin-on, inline or in-tank, and primary or secondary. As I mentioned above, the mounting style and design of the fuel filter depends on a couple of factors, including vehicle type, model, year, and type of fuel system.
New vehicles feature fuel filters that are different from older ones, both in terms of position and design. Older carbureted cars have the fuel filter somewhere along the fuel line, whereas modern cars house it inside the fuel tank. Types of diesel feature filters that look and operate differently from petrol engines in that they’re larger in size and bowl-shaped rather than canister or cartridge-shaped.
Depending on the vehicle’s fuel system, the filter may be primary or both primary and secondary.
These filters are generally used in diesel fuel systems, and they’re tasked with removing contaminants like wax and water. They’re positioned on the vacuum side of the pump, meaning they also protect the pump from contaminants that can damage it or wear it down.
Primary fuel filters aren’t as restrictive simply because they precede the secondary filter and don’t need to filter the smaller impurities. In other words, most primary filters can only remove particles larger than ten microns.
These filters are also used in diesel, and their purpose is to block the smaller impurities that pass through the primary filter. That being said, they’re fitted with tighter media, and they’re positioned on the pressure side of the pump, which is typically closer to the engine. They don’t remove water, but the particles that are smaller than 10 microns.
Fuel filters are simple devices that are made up of just a few parts. Petrol filters are the most basic, as they don’t require a water-extraction mechanism to separate water from the fuel. Some fuel systems use both primary and secondary fuel filters to decontaminate the fuel, while others use a single filter – a primary one that removes everything in one go.
Also, there are systems that use a typical filter and give you the option for a water separator. Petrol systems use a single filter simply because petrol is cleaner than diesel and doesn’t contain wax and water.