Mr. Slade still taking arrows being out front...thanks (clogged fuel filter)

[Edge 513]

 

Prior to refueling, take a look at the screen, then when you refuel, point the fuel nozzel at the screen to wash it off.

 

 

Waiter

When you wash it off with the fuel stream, where does -it- go?

[Waiter]

When you wash it off with the fuel stream, where does -it- go?

 

Nowhere, it stays in the strake. If its soluable, sooner or later, it will desolve to a small enough particle and will go through the screen. Otherwise, it stays in the strake.

 

NOTE- I seen a small leaf one time (How in the heck did that get in there?????), that s the only time I've ever seen anything on my screens.

 

Waiter

[Terry]

The purpose of the fuel tank screen is to prevent the fuel line from getting plugged so that screen should be fairly coarse. All certified airplanes have a screen of about 1/8th to 3/16th mesh size. It is basically there to catch the big stuff that would plug the fuel line or valves and such. The strainer and other down stream filters that can be easily cleaned catch the fine stuff.

Terry

[Lynn Erickson]

The purpose of the fuel tank screen is to prevent the fuel line from getting plugged so that screen should be fairly coarse. All certified airplanes have a screen of about 1/8th to 3/16th mesh size. It is basically there to catch the big stuff that would plug the fuel line or valves and such. The strainer and other down stream filters that can be easily cleaned catch the fine stuff.

Terry

most all aircraft have a finger strainers in the tank outlet and are 16 mesh screen. The wire centers are 1/16" apart with about a .055" opening. this is to protect the lines from foreign matter that gets into the tank from refueling.

[Edge 513]

most all aircraft have a finger strainers in the tank outlet and are 16 mesh screen. The wire centers are 1/16" apart with about a .055" opening. this is to protect the lines from foreign matter that gets into the tank from refueling.

Well thats a bit better than, "go get a hardware store type screen" as directed by the plans. Then theres the question of some guys putting in a screem that is too fine.

[David Clifford]

Which begs the question, "What size of particle is detrimental to the pump and might a coarser filter before the pump and a finer one after do well? Is that Andair part aviation or other??

Andair is aviation stuff. The pump/filter we put in the Cozy is Airflow Performance. Yes we put finger strainers in the tanks but we followed directions the installing recommendations by the mfg and placed the filter pre-pump. The point I am trying to make is that for whatever reason, the replacement filter cartridge was finer than the original,,,,,so must finer to the point that it interfered with the fuel flow enough that the engine mounted diaphram pump could not draw enough fuel to generate enough pressure. Under no circumstances would I place the fuel filter after the electric pump. Your just asking for early pump failure doing something like that

[argoldman]

Andair is aviation stuff. The pump/filter we put in the Cozy is Airflow Performance. Yes we put finger strainers in the tanks but we followed directions the installing recommendations by the mfg and placed the filter pre-pump. The point I am trying to make is that for whatever reason, the replacement filter cartridge was finer than the original,,,,,so must finer to the point that it interfered with the fuel flow enough that the engine mounted diaphram pump could not draw enough fuel to generate enough pressure. Under no circumstances would I place the fuel filter after the electric pump. Your just asking for early pump failure doing something like that

HUH????

 

How does pulling through a restriction differ than pushing through a restriction in terms of pump longevity????

 

In the real world of fluid stuff, the fuel pressure is a measure of the pressure due to the restriction of the fluid flow between the pump and the orifice in the carb or fuel injector unit. That's a lot of back pressure. In a carb that may be only a couple of PSI, but in a fule injector it may be in excess of 25-45 PSI. IN fact, the pump puts out more pressure than this and the overage is returned back to the tanks, either by a relief valve at the pump or by a relief valve at the fuel rail (in most EFIs) The fuel pressure is a measure of what the relief valve allows through to the system (set primarily by the relief valve).

 

The pumps are designed to handle that (check the specs of the pump)(or at least they should be) If there is enough crap in a down stream filter to significantly increase that pressure there is something wrong"er" with the system. The pre-pump filter is designed to keep out particulate matter that would harm the pump. The tank filter screen, or finger screen keeps out the big chunks, the concept of which has been described before. The finer mesh filter is designed to keep the tiny-tiny chunks that have the ability to clog the FI system, or the injector nozzles with their tiny orifi.

[David Clifford]

HUH????

 

How does pulling through a restriction differ than pushing through a restriction in terms of pump longevity????

QUOTE]

Let me try to explain this to you .. Did I say anything about pushing vs pulling had anything to do with pump longevity????? No. I know that the finger strainers trap only the biger chunks. What I said was that the replacement filter screen was a much finer mesh than the original that came with the unit. So much so that the screen itself created enough restriction to hamper fuel flow to the point that the mechanical engine driven fuel pump could not produce enough pressure to run the engine at cruise power. Maybe you would rather filter after the electric pump but I think I will follow recommended proceedures and filter before it reaches the pump where debris can trash the $400 + pump. No thanks!

[argoldman]

HUH????

 

How does pulling through a restriction differ than pushing through a restriction in terms of pump longevity????

QUOTE]

Let me try to explain this to you .. Did I say anything about pushing vs pulling had anything to do with pump longevity????? No. I know that the finger strainers trap only the biger chunks. What I said was that the replacement filter screen was a much finer mesh than the original that came with the unit. So much so that the screen itself created enough restriction to hamper fuel flow to the point that the mechanical engine driven fuel pump could not produce enough pressure to run the engine at cruise power. Maybe you would rather filter after the electric pump but I think I will follow recommended proceedures and filter before it reaches the pump where debris can trash the $400 + pump. No thanks!

 

 

I guess I misinterpreted your statement of "Your just asking for early pump failure doing something like that" I was assuming a proper pre pump filter as well as a post pump finer filter. So much for assumptions:(

 

Now the question comes, since you replaced one screen with one of a finer mesh, is the screen that is proper for protecting the pump, I assume that was what you had originally (which I agree is necessary), of fine enough mesh to protect the fuel injection regulators and injection nozzles? (why the availability of the finer mesh??).

[David Clifford]

 

 

I guess I misinterpreted your statement of "Your just asking for early pump failure doing something like that" I was assuming a proper pre pump filter as well as a post pump finer filter. So much for assumptions:(

 

Now the question comes, since you replaced one screen with one of a finer mesh, is the screen that is proper for protecting the pump, I assume that was what you had originally (which I agree is necessary), of fine enough mesh to protect the fuel injection regulators and injection nozzles? (why the availability of the finer mesh??).

 

We don't know why the replacement mesh was finer. The original pump/filter came as a package. There was no information that various screen sizes were available when the new one was ordered. We should look into that with Airflow Performance.

[Waiter]

I think the references to the "Finer Screen" are what I installed originally in the strake, not finger strainers. When I built my strakes, I used a fine mesh (40 per inch???) screen instead of the "Window Screen". I would caution anyone else using the finer screen to make sure you supply plenty of screen area, to allow fuel passage through a partially plugged screen. Also mounting the screen at an angle will allow any sloshing of fuel to help clean the screen.

 

The Airflow Performnce system I installed during my retrofit has a very fine mesh "Filter" that should protect the injectors and servo.

 

Thoughts - If there is ever enough crap in the fuel to plug both strake sump screens, this amount of crap would have easily plugged the carb filter and fouled the carb venturi. (or, clogged the fuel filter and fouled the fuel injectors)

 

Waiter

[argoldman]

I think the references to the "Finer Screen" are what I installed originally in the strake, not finger strainers. When I built my strakes, I used a fine mesh (40 per inch???) screen instead of the "Window Screen". I would caution anyone else using the finer screen to make sure you supply plenty of screen area, to allow fuel passage through a partially plugged screen. Also mounting the screen at an angle will allow any sloshing of fuel to help clean the screen.

 

The Airflow Performnce system I installed during my retrofit has a very fine mesh "Filter" that should protect the injectors and servo.

 

Thoughts - If there is ever enough crap in the fuel to plug both strake sump screens, this amount of crap would have easily plugged the carb filter and fouled the carb venturi. (or, clogged the fuel filter and fouled the fuel injectors)

 

Waiter

A little semantic problem here, sorry.

 

When I refer to screen, with the exception of the initial course screen at the strake outlet, (I am using finger strainers since they can be cleaned )I am referring to the screen element in a fuel filter. These are actually folded metal screens albeit it perforated, probably by a laser, through which fuel is pumped (or sucked).