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  #1  
Old 05-06-2021, 09:12 AM
Kahuna's Avatar
Kahuna Kahuna is offline
 
Join Date: Dec 2004
Location: Gold Hill, NC25
Posts: 2,418
Default Reusable AFP fuel filter and solvent

Over the past 500 hours or so I have noticed a slow progressing need for the boost pump, culminating in fuel starvation and an uneventful landing on a recent cross country.

A check of the fuel line at the servo and boost pump on resulted in fuel shot across the ramp. Seemed fine. Test flight, and again fuel starvation.

A check of the fuel filter show nothing. Visually spotless. Until I tried to blow through it. Definite restriction. Cleaned filter with carb cleaner, and I could see a light yellow color in the solvent. Reassembled, and no restriction blowing through it. Problem solved. Flown another 10 hours until home with no need at all for the boost pump which is something I had not seen in years.

This is an AFP 40 micron filter. One of those 6ILA assemblies.

I checked the paperwork for cleaning instructions and "The filter element can be removed from the filter cap and cleaned in mineral spirits then blown dry with compressed air"

Hmm. "Can be"

Checked with a couple other high time experienced RV'ers, and they too had never run solvent through the filter.

With 2500 hours over 20 years on the filter, I have never done more than visual inspection, clean off any debris, and reinstalled. Never any solvent. I have no idea what had been building up in inside the element, but obviously something had. Also no indication in the docs about service life. Installed a new one.

Lesson?
1. Dont let a slow creeping issue go unresolved.
2. Clean the filter with solvent at annual.
3. After assembly, blow through the housing, it should blow quite freely.
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  #2  
Old 05-06-2021, 09:16 AM
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Default ....and

Also check the screen at the FI servo inlet...
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  #3  
Old 05-06-2021, 09:25 AM
BillL BillL is offline
 
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Location: Central IL
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Default Dissolve what gasoline won't.

Thanks for that information. The solvent should be more "aggressive" than mineral spirits or it may dissolve nothing.

Knowing that the spray carb cleaner works is my key takeaway.

This leaves curiosity about just what yellow substance/particles could exist in gasoline and plug this filter. Is it mogas fueled, 100LL or both?

The standard filter is 74 micron, any reason for the 40?

You say a new one was installed, was the carb cleaning solvent not satisfactory, or just precaution (nothing wrong with that).

Is there slosh or some regular use of ez-turn that might accumulate? ez-turn is a liquid polymer, polypropylene I think. Maybe it could shed and plate the filter. It could only come from caps, or limited sources to hit this filter.

Yes the final answer - is to clean and replace the darn filter !!
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Last edited by BillL : 05-06-2021 at 09:46 AM.
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  #4  
Old 05-06-2021, 09:39 AM
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Kahuna Kahuna is offline
 
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Default

Quote:
Originally Posted by BillL View Post
This leaves curiosity about just what yellow substance/particles could exist in gasoline and plug this filter. Is it mogas fueled, 100LL or both?
I have never run mogas in it.
Coarse screen at the servo inlet was clean.
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  #5  
Old 05-06-2021, 09:41 AM
TS Flightlines TS Flightlines is offline
 
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Default

Back in the automotive days, I used to use alot of carb/injection cleaner. WE found that auto fuels, would leave some gummy residue, and color like Kahuna mentioned. Even soaking a carb in the those submersible cleaners didnt clean the residue like carb cleaner. Extra care to NOT get it in cuts, eyes etc!
Been doing it that way for +45 years. Works very well on stainless screens.

Tom
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  #6  
Old 05-06-2021, 10:00 AM
Freemasm Freemasm is offline
 
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Location: Orlando
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Default

Is the just a screen or is there any other media. Can't tell from the picuture.

The "Cleaning" procedure from the OEM most certainly had to do with flushing particulate away. Your situation is different. BillL is probably correct regarding some substance is being suspended and depositing on the element parent material. Filters are areas of relatively low fluid velocities so that doesn't help. I'd bet slosh if no corresponding fuel system maintenance has been done in this timeframe.

Also, double check the required filter beta rating. Finer (higher number) isn't necessarily better. It can be acceptable but typically you'd want to increase filter media surface area; bigger canister.
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Old 05-06-2021, 10:16 AM
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rv8ch rv8ch is offline
 
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Default

Anyone know what the filter size is at the fuel station pump? I guess there must be a standard, and I'm guessing it's bigger than 40 micron.

We had a presentation from a guy from Total at our chapter meeting a couple of years ago, and it kind of scared the Árap out of me. He had some horror stories that he used to emphasize how they (Total) take extra precautions to not have problems with their fuel.
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  #8  
Old 05-06-2021, 10:25 AM
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Kahuna Kahuna is offline
 
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Quote:
Originally Posted by Freemasm View Post
Is the just a screen or is there any other media. Can't tell from the picture.
There is multiple media in the filter. An outer screen mesh, and something else inside. Some kind of fine woven mesh, hard to discern.
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  #9  
Old 05-06-2021, 10:37 AM
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Kahuna Kahuna is offline
 
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Quote:
Originally Posted by BillL View Post

The standard filter is 74 micron, any reason for the 40?

You say a new one was installed, was the carb cleaning solvent not satisfactory, or just precaution (nothing wrong with that).

Is there slosh or some regular use of ez-turn that might accumulate? ez-turn is a liquid polymer, polypropylene I think. Maybe it could shed and plate the filter. It could only come from caps, or limited sources to hit this filter.

Yes the final answer - is to clean and replace the darn filter !!
Years ago, I had a 6a that i put ~2k hours on. I had problems with the pumps every 500 hours getting really noisy. One failed. I believe it was Charlie Kuss that was knowledgeable on them and suggested a finer filter. So I went to 40. That stopped the pumps getting eaten. I ran the pump mostly always due to the flying environment it was in mostly. Low level with other planes.

No, no slosh in this plane. Yes EZ lube used as rarely as maintenance seemed necessary. Nothing I would deem as excessive. But of coarse that lube is going somewhere.

Yes the carb cleaning solvent did work. In fact very well as I mentioned. I replaced the filter just cause I didnt trust it.
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Old 05-06-2021, 10:43 AM
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Skid Skid is offline
 
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"Cleaned filter with carb cleaner, and I could see a light yellow color in the solvent. Reassembled, and no restriction blowing through it. Problem solved."

Kahuna, wondering if you submerged the entire filter with the o-ring on it. If so the yellow discharge may have come from the o-ring. Carb cleaner is a very aggressive cleaner and can attack rubber compounds.
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