How do I choose the right fuel filter?

Filtration is an essential consideration when upgrading your fuel system from carbureted to EFI.

 

Many older OEM filters are not rated for the pressure of EFI systems. Most OEM replacement filters are not rated for the pressure of a boosted application fuel system. Make sure to choose an aftermarket filter that is rated appropriately for your needs.

 

Fuel filters are rated for filtration by the average pore size of the filter element. 100 microns is great for pre-pump, but some newer pumps will require finer, such as 80 micron.

 

Choosing a filter that has the proper element is crucial. Not all filter element materials can withstand higher fuel pressures, ethanol or race gasses.

 

The best filter elements are stainless steel and microglass. Cellulose is the most common, however. A cellulose filter is not recommended for use with ethanol fuels because both contain organic compounds. This can create a bio sludge that wreaks havoc on downstream fuel system components.

 

Multi-Port Fuel Injection (MPFI) fuel injectors require 10-micron filters positioned after the pump, while Gasoline Direct injection (GDI) injectors require 5-micron filters.

 

There are no fuel injector manufacturers that recommend any fuel filter over 10 microns.

 

Many OEM MPFI applications will not have a fuel filter after the pump. These applications generally do not have a filter finer than 100 microns. OEM applications generally use majority hard lines and do not have fuel pumps with extremely high flow, so they don’t need the 10-micron filter and rely on a tiny filter basket atop the fuel injector for injector protection. This is insufficient for high flow fuel systems.

 

High performance OEM vehicles will have a fuel system with a 5-10 micron filter post pump and pre-fuel rail. One example is the Chevy Corvette C6 and up.

 

When adding a much higher flow pump and injectors, it is crucial to upgrade the fuel filter accordingly. The higher volume of flow as well as the increased suction of the pumps means a higher likelihood that contaminants in your tank or lines can make their way into your fuel injectors and cause a failure.

 

A failed fuel injector can cause catastrophic engine damage!

 

MPFI fuel injectors require 10 micron fuel filters with an appropriate element for the fuel you intend to use.

 

GDI fuel injectors spray directly into the combustion chamber and have finer internal tolerances. This requires finer filtration. 5 micron is standard.

Parts Dealer Links

 

In-Tank Fuel Pumps

https://www.snakeeaterperformance.com/collections/fuel-pumps

 

Retrofit Fuel Tank Units

https://www.holley.com/search/?q=retro%20fit%20fuel%20tank

 

Filters and Filter Fittings

https://www.snakeeaterperformance.com/collections/fuelpump-fittings-and-filters

 

Fuel Injectors

https://www.snakeeaterperformance.com/collections/all

 

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Fuel injectors, carburetors, and electric fuel pumps can be harmed by relatively small particles. To keep your car running at peak performance you need to choose a filter with the right micron rating and element type.

Micron Ratings

A micron is so small it can’t be seen by the naked eye. Micron ratings on filters typically range between 2 and 100. The lower the number, the smaller the particle it will filter out reliably. You don’t always want the lowest micron filter you can get because they can clog up. Follow these recommendations depending on where the filter is and what type of fuel system you have.

• 100 Micron Filters are usually used as pre-filters to protect fuel pumps and keep larger debris from clogging your post-pump filter. They can be mounted in-line before the pump or in the tank. Pre-filters in the tank are often called “sock filters” or “fuel strainers”
• 40 Micron filters are generally used for carbureted engines after the fuel pump. It’s a good idea to use these along with a 100 micron pre-filter even with a mechanical fuel pump.
• 10 Micron Filters are used after the fuel filter with fuel injected engines and must be used along with 100 micron pre-filter.

Filter Element Types

When choosing your filter’s element material you should consider fuel compatibility, reusability, and position in your fuel system.

• Paper filters are often referred to as cellulose filters and are usually disposable.
  • Paper filters should not be used with methanol or fuels containing more than 20% ethanol
• Stainless-steel filters are compatible with all fuels and can typically be cleaned and reused.
• Micro Glass filters are for post-pump use only and are disposable. 

Fuel Filter Elements and Compatible fuels

 

Fuel types

Filter Element type

 

 Stainless Mesh

 pre / post pump

  Paper / Cellulose

 pre / post pump

   Micro Glass

 Post pump only

Pump Gas And Race gas

87 octane to 120 octane

x x x Diesel Fuel x x x Methanol x   x Ethanol and Ethanol Based fuels (E85) x   x