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Old 07-07-2019, 06:23 PM
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Question
Clogged carb screen

How doe a carb screen get totally clogged when I have 4 filters...

1. Filter in the fuel jug inside

2. Fuel filter on the outside of fuel jug

3. Filter clunk in planeís fuel tank

4. Filter between the fuel line T and the engine...

How does the carb screen get clogged...???
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Last edited by les2097; 07-09-2019 at 03:00 PM.
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Old 07-07-2019, 07:51 PM
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If your felt clunk fails it can shed fibers into the carb. Orthobird had a thread on this awhile back. I’ve moved to ceramic clunks.
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Old 07-07-2019, 08:15 PM
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Quote:
Originally Posted by les2097 View Post
How doe a carb screen get totally clogged when I have 4 filters...

1. Filter in the fuel jug inside

2. Fuel filter on the outside of fuel jug

3. Filter clunk in planeís fuel tank

4. Filter between the fuel line T and the engine...

How does the carb screen get clogged...???
What was it clogged with? Certain gasoline formulas and old gas can sometimes leave an almost clear coating on the screen and filters do not prevent this. This is a chemical problem, not a foreign body problem. This sort of problem usually shows up after a carb has set unused for a time. Was it dirt, fiber or whatever in the carb?

Iíve used felt and ceramic filters for years in airplanes, saws and yard equipment. Zero problems and never a fiber in a carb.
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Old 07-07-2019, 09:56 PM
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Quote:
Originally Posted by les2097 View Post
How doe a carb screen get totally clogged when I have 4 filters...

1. Filter in the fuel jug inside
2. Fuel filter on the outside of fuel jug
3. Filter clunk in plane’s fuel tank
4. Filter between the fuel line T and the engine...

How does the carb screen get clogged...???
Good comments from Truckracer.

Note also that the internal carb filter can be very fine, and it's also flat-ish or slightly domed in shape. If it's a 30 micron filter, for instance, and you are using 60 micron filters elsewhere, the finer particles will pass through and end up on the interior filter. Also, the shape and orientation of the filter media can allow certain types of debris pass that will not go through a flat-shaped filter screen.

Lastly, you say you are using (4) filters. What types are they? If the in-tank filter is a felt clunk, there are some older Walbro ones and some non-Walbro generic ones that shed fibers and may clog the internal carb screen. If you use a genuine Walbro #125-534 or 125-532, those will have 2 layers of felt plus internal 30 micron stainless screens. The felt on these has been cut in such as way as to minimize or eliminate shedding of loose fibers.
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Old 07-07-2019, 10:42 PM
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I had one clog from a fuel line flaking from the inside. It was a line that came with a plane and it was junk.
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Old 07-07-2019, 11:44 PM
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Additives in the fuel even the oil you use ,some have what’s called plating action
Which adheres itself to metal parts ,it cam also adhere to the screen
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Old 07-09-2019, 01:01 PM
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Details...

Felt inside the gas can; auto paper on the gas can outside; ceramic inside fuel tank and gold one I bought from hobby shop for gas engines between
The fuel T and engine...

The screen was clogged with a sort of lightish brown substance...

I fly this plane 2 or 3 times a week...

Non ethanol fuel 87 octane...

Redline oil at 43:1...
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Old 07-09-2019, 02:31 PM
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Replace the filter, they are common parts. Can they be cleaned? Yea, but if you don't do it properly they look clean but are still clogged since the filter is so fine
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Old 07-09-2019, 02:59 PM
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I have replaced the carb filter and engine runs fine again...

BUT WHAT is clogging the filter... with four filters in my system from gas can to engine..,?
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Old 07-09-2019, 04:28 PM
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Varnish like materials and other substances in some gasoline formulas can interact with oils and form a material that will clog a screen. These are part of the gas formula and pass through most external filters but somehow form a layer on the screen that fuel will not pass through it. You might try a different fuel source. Anybody that has worked on small engines very much knows about the mysterious slime layer on the screen. But no, I don’t really know where it comes from. One source is incompatible oils that congeal over time.
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Old 07-09-2019, 05:53 PM
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I use seafoam in my yard stuff and im using it in my plane fuel, I cant give any long time use info other than ive used about 3 gallons so far
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Old 07-09-2019, 06:23 PM
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Quote:
Originally Posted by les2097 View Post
I have replaced the carb filter and engine runs fine again...

BUT WHAT is clogging the filter... with four filters in my system from gas can to engine..,?

Most common name for it I've seen is "that clear gook that plugs your carb screen".
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Old 07-09-2019, 06:43 PM
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Quote:
Originally Posted by AHicks View Post
Most common name for it I've seen is "that clear gook that plugs your carb screen".
Now that's an informative scientific analysis...ROFLMAO
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Old 07-09-2019, 08:41 PM
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Some questions just don’t have convenient canned answers. I rather liked Ahicks answer. Short and to the point with a bit of humor.
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Old 07-09-2019, 08:47 PM
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If this was a distillate like diesel fuel, a problem like this could be caused by a bacteria caused slime in the fuel. I’ve never heard of bacteria related problems in gasoline though. We use to have some fuel experts on here but I think they’re all gone now.
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