Thread: Fuel Filter Advice - TeamKitfox Forums

Kitfox Folks,

I'm looking for testimonials and field experience about fuel filters. What type & brand of fuel filter do people use and why? My latest favorite is the bronze filter element that can be installed in the engine compartment if desired (or anywhere else) and can be removed for inspection and cleaning, such as Earl's aluminum body with bronze insert. I have a technical bias against paper elements however they are being widely used. What do others use?

Thanks much,

Skot

I have glass fuel filters mounted in the down lines from each wing tank to the header tank. My lines run down along the top of the quarter window. The filters are visible as I fly and in low fuel situations as in long down runs from the Sierra crossing to home, I can visibly monitor fuel flow. I also have the finger strainers in the tanks. 900 hours on the first Model IV with this set-up and not a hiccup.

I do have one of the filters you describe, but it came with my second hand kit and it is still in the box as I like to see what is going on without taking things apart.

My preference is a combination of both Lowells and Toms.

I like the visibility aspect of Lowells and it provides the ability to supply fuel if one filter becomes clogged.

I believe a gascolator is necessary, but I do remove the mesh inlet filter as no need to filter twice.

A few other points to ponder:

Rotax recommends a 100 micron (.1mm) for 4 strokes. Most would find anything between 70 and 100 micron acceptable. Any finer and you are increasing the probability of clogging and the required maintenance un-necessarily.

I agree paper filters should be avoided - most are far finer than 100 micron and can clog much faster and trap water much easier. It is beyond me why places like Aircraft Spruce even sell them.

I would also never use a plastic or glass filter housing in the engine bay.

If using electric fuel pump(s) many have a pre-filter built into the inlet (ala 914 Pierburg pump). If you have an electric pump chances are it has one and it may be required by the pump manufacturer - it is another maintenance item.

If you have another type of fuel system - IE injected - follow the manufacturers recommendations to a tee. Many injectors require much finer filtering than a carbureted engine.

Incorrect filter micron selection/maintenance may be the cause of some rough running installations. How many even know the micron size of their filters?

All IMHO, YMMV!
Greg

I use the filter provided in the factory SS7 FWF kit for the 912. It is a NAPA inline filter in a metal housing, mounted at the inlet to the fuel pump per the build manual. Finger strainers are also include in the outlet of each fuel tank.

I personally don't believe a gascolator is necessary (neither does the factory) because you don't need to filter twice and the header tank with its drain at the lowest point in the system does the same job as a gascolator for water separation/draining.

You are right, I include draining a sample out of the bottom of the header tank as part of every pre-flight checklist. I also agree a gascolator is not going to hurt anything as a belt and suspenders approach, but it is another maintenance point to deal with. If you have a gascolator, I believe you should still also drain the header tank on a regular basis because it will separate water and that water will lay in the bottom of the tank up to the level at which the outlet fitting to the engine is located (about 1"). This can be a lot of water and if it is not drained, it could suddenly overflow into the engine feed line and possibly even overwhelm your gascolator. I believe in the KISS principle and prefer to drain preflight samples in just the 3 spots-header tank and 2 wing tanks.

Some people say that a gascolator can be located at a lower point in the fuel system than the header tank, and I suppose this may be true on some airplanes. It also may be true on a tricycle gear airplane. Most of the water is going to separate during periods of sitting on the ground, and a taildragger like mine sits with the header tank drain being the lowest point, so I am very comfortable without a gascolator.