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  #1  
Old 04-25-2009, 01:36 PM
frankh's Avatar
frankh frankh is offline
 
Join Date: Jul 2006
Location: Corvallis Oregon
Posts: 3,547
Default Worm in my fuel system

Hi Guys,

As you know I am the driving force behind the wingroot fuel pump system. Yesterday I had my first issue.

I thought I had a failed fuel pump after takeoff fom Hillsboro airport in Oregon. No problem as the sytem is designed with two independant fuel sources so I flew the half hour home on the one good pump. I climbed to 7500ft as this put in me gliding range of an airport for all of about 5 minutes on the trip and I loaded the tower/CTAF freq of each airport as I had it made dead stick if I had to.

Anway..I removed the fuel filter upstream of the offending pump and voila, the issue was a plugged filter from a length of proseal that had had flaked off, looked like where I had prosealed on the cover as it had that shape.

Interesting to me was that this "worm" of proseal was enough to plug the filter.

I remember I had changed to this sintered bronze in line filter at the same time I started using an E10 (ethanol blend) auto fuel. I was a little concerned at the time because the filter was much smaller than the paper disposable type I had been using before and the bronze element went almost up to the incoming tube of the filter housing..Good enough for fine particles, but not enough room to allow for a worm to enter the filter housing..I,e the worm really plugged the 3/8ths tube ahead instead of the filter itself.

So I am considering changing back to the paper disposable type...I only changed to the sintered bronze type because I read somewhere that water could cause a paper element to swell and cut off the fuel flow.

I can't seem to find a SB filter that has both lots of filter area and plenty of room to accomodate a worm (unless anyone can tell me where to get one) that will fit in the wingroot with all the other stuff.

So The next best thing is I am going to declare an experiment..Namely I am going to take the pair of old paper element filters that I kept and drop them into a bucket of water overnight and see if the pressure drop thru the filter goes up significantly. I will test the PD by the highly accurate method of blowing through the filter..


Any helpful comments..By which I mean not those like "You've modified the fuel system so your surely going to die" type coments are welcome..

Frank
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  #2  
Old 04-25-2009, 02:17 PM
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Walt Walt is offline
 
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Location: Dallas/Ft Worth, TX
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Default Hmmm...

I would have thought the strainer on the fuel pick up in the tank would have caught something like this (assuming you are using one). I used the one that van's sells as they have about a 2" screen on the end that would stop big stuff but allows plenty of additional area to let the fuel keep flowing.
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  #3  
Old 04-25-2009, 02:26 PM
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Ron Lee Ron Lee is offline
 
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Default

What Walt said. Please provide a better description of the in-tank screen if any and a picture of the proseal plug.
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  #4  
Old 04-25-2009, 04:33 PM
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frankh frankh is offline
 
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Default No strainer

I have flop tubes in both tanks which have 1/8th holes in the brass weights from memory.

Its amazing that a worm would find its way through those holes but it clearly did.

Frank
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  #5  
Old 04-25-2009, 04:37 PM
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frankh frankh is offline
 
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Default Oh the worm

I just looked at and it looks to be 1/16th in diameter and about 5 inches long..Clearly it bundled up into a ball as it couldn't enter the filter.

Frank
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  #6  
Old 04-25-2009, 05:52 PM
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az_gila az_gila is offline
 
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Exclamation Perhaps an Earls...

...fuel pre-filter might help before your sintered bronze one?

It's a screen type, with a mesh similar to a gascolator.

http://www.streetperformance.com/par...08-230206.html

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  #7  
Old 04-25-2009, 09:50 PM
David-aviator David-aviator is offline
 
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Location: Chesterfield, Missouri
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Default

Quote:
Originally Posted by az_gila View Post
...fuel pre-filter might help before your sintered bronze one?

It's a screen type, with a mesh similar to a gascolator.

http://www.streetperformance.com/par...08-230206.html

I am using an Earl's screen filter before the electric pump, so far so good. I also have the AFP filter in the pump by-pass line which gets used when the electric pump is off, also so far so good.

Seems like a paper filter might be asking for trouble. Don at AFP says in the book don't do it. I nearly crashed a C150 once when a paper intake filter got wet....water may be reason paper is a no-no in the fuel system.
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  #8  
Old 04-25-2009, 10:00 PM
scsmith scsmith is offline
 
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Location: Ashland, OR
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Default suggested extra test

I would propose that you test a paper filter that has been exposed to water prior to any exposure to fuel, and then, test a filter that has been kept wet with fuel, then exposed to water.

My thinking is that if the paper element is wet with fuel, the water can't get to the paper and 'seal' it.

I remember these special funnels for filling camp stoves and lanterns. they had a brass screen in them, and if the screen was wet with water, fuel would not go through the screen. If you dried all the water out of it, then fuel would go through.

Operationally, I'm not sure if it is sufficient to be sure that the tank is never allowed to run out of fuel so the filter always stays wet with fuel? What do others think about this?
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  #9  
Old 04-25-2009, 10:31 PM
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RVAddict RVAddict is offline
 
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Default

Quote:
Originally Posted by David-aviator View Post
I nearly crashed a C150 once when a paper intake filter got wet....water may be reason paper is a no-no in the fuel system.
Are you talking about the air filter on the front of the cowling? If so, why would it have a paper filter? Was the carb heat broken?

Thanks,
Josh
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  #10  
Old 04-25-2009, 10:55 PM
asav8tor asav8tor is offline
 
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Default

This is the reason I am against running a tank dry. I want to have an option to switch tanks, to a tank with fuel, if fuel from one tank stops feeding for any number of reasons.

I think your worm is a first.... but perhaps not the last of such type events.
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