Fuel Filter Dirt Pattern

[SPICER]

Has there been any conclusion as to why an OE fuel filter has the dirt pattern that it does? After cutting them open they show a dirty bottom half and a clean top half. Is this because the filter is only 1/2 full or is it that the dirt is settling out? Anyone with a lift pump observed a different dirt pattern? Just curious. SPICER

[mdrag]

Spicer,

As you know, the OEM fuel filter operates in a suction/partial vacuum environment. As such, the filter is only partially full of fuel, and the media is used from the bottom to the top. Bottom and top refer to the position of the filter media as installed on the Dmax. The 'stripes' extending from the top of the media occur where the fuel enters the filter and trickle down the side of the media.

Check out the BALDWIN TSB (http://baldwinfilter.com/engineer/pdf/94-6r.pdf) explaining suction/vacuum side fuel filters.

There are many pics of cut open filters at the second link in my sig - including OEM's with lift pump use. As expected, pressurizing the fuel system with a lift pump results in even media use and no 'banding'.

[MaxACL]

Would it be prudent to add a pump close to the tank to help push the fuel through? This would be especially helpful to me since the pick-up tube on my 115 gal tank is an inch or two from the bottom then it must travel up (by suction) and over the top of the tank (level with the bed rail) then down to the fuel line. I want to install a hose at the bottom (drain plug) of the tank via a pump then continue it's trip to the engine. Otherwise I have about 20 gallons of fuel in the bottom of the tank that I can't count on because I will starve the engine in hilly country.

The fuel line on my airplane is 4.5 inches (diameter) and puts out 6000 pounds/min at 60 psi. Some of my clients get real thursty! :D

But back to the question... Any harm in adding a lift pump?

Mike