# How many Microns ?



## noeettica (Sep 23, 2007)

Any one have any thoughts on fuel filter Micron ratings 

Dave


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## Brett (Jul 16, 2008)

Yep....



           ....oh, you actually want my opinion, sorry.  

I go with a standard fuel filter on my carbureted engine.
With fuel injection I'd want something a bit tighter.
I'd check with the manufacturer for their recommendations.

A good quality filter, even if not the best, is better than no filter.

http://www.boatpartsinfo.com/fuel-filters.html



> "A 30 micron filter (or primary filter) is used to filter raw fuel (or poor quality fuel) before it can be further filtered by finer medias such as a 10 or 2 micron. A 10 micron filter (or secondary and even final) is used to filter fuel which is known to be of very good quality. A 2 micron filter (or final filter) is the finest filtration available and is the last filter used prior to engine ingestion." In other words, the first filter in line from the fuel tank (primary) should have a larger micron rating than the filter (secondary) located further on down line or on the engine. The secondary filters are commonly 10 micron rated. If you use a 2 micron primary filter, a larger micron rated secondary filter will be doing absolutely nothing while reducing the overall efficiency of your system. The primary filter should be either a 10 micron or 30 micron rated filter. Keep in mind that using the small micron rated filters will also require more frequent filter changes. Exceptionally high fuel-flow engines, such as Detroit Diesels, should use the largest micron rating as the smaller sizes will restrict fuel flow and will need to be changed more often than necessary. Remember, it is fuel flow, not fuel consumption that determines the correct size of the fuel filter/water separator unit you use. Many engines use a fuel bypass system that routes unused fuel back to the fuel tank after it passes through the filtering system. Additionally, many small diesels are equipped with equally small fuel lift pumps. Using a small micron rated filter increases the load on these small pumps which can lead to premature failure. A properly sized primary filter used in conjunction with the engine mounted secondary filter will provide all the filtration needed to guarantee good fuel quality.



Thanks Dave, I never gave it much thought before.


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## iMacattack (Dec 11, 2006)

Every manufacture I worked with for our Four Stroke Shootout agreed, 10 micron!


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## noeettica (Sep 23, 2007)

I Will Be using my Fram HPG1 In the Rig of my Classic ... 

Dave


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