# Sticky  Hidden Carburetor Fuel Filter Screen On Small Engines! Must see!



## 3vanman

I have cleaned several of these newer carbs, and all I can say is "guess I've been lucky".
This video was posted by Donyboy73 yesterday.
Definitely a must see if your working on a newer MTD or Cub Cadet or such..as they share the same carb. 


*Hidden Carburetor Fuel Filter Screen On Small Engines! Must see!*
Hidden Carburetor Fuel Filter Screen On Small Engines! Must see! - YouTube


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## JLawrence08648

You beat me to it! I watched this just a few minutes ago. Everyone, watch this. The fuel line inlet elbow comes out and behind there there is a metal screen that gets clogged. Dony said he didn't know about it at first. I have a power washer that no fuel is coming out the inlet valve, blew it out with carb cleaner, started flowing, put the fuel bowl back on, then it stopped. I'm sure this is what is wrong. This particular engine, to remove the carb, I have to remove the entire engine because of the handle framing. This will save me!


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## ST1100A

Wow you can tell 'Donnyboy' is new at cleaning carburetors because almost every carburetor always had them there and that is the most common place for fuel line dirt to accumulate at.
But that is good he showed people about cleaning that area. That is the very first thing we do when working on any carburetor, is to clean that passageway/fuel inlet.
It is a 'Finer' screen than the screen in the fuel tank. They are the most common thing to clog in tiny 2 stroke carburetors used on 'Micro Engines' used on weed trimmers and chainsaws plus many other things.


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## tabora

ST1100A said:


> almost every carburetor always had them there


Yup, the Honda carbs with the sediment bowl have a very effective secondary filter in there, too.


02716959-Z5T-901FILTER, CUP


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## 140278

how many times have we had our members post about it? screws into the tank as the nipple


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## tabora

captchas said:


> how many times have we had our members post about it? screws into the tank as the nipple


Yup, that's the primary and the one at the carb is the secondary...


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## rwh963

is there a screen like this hidden on small carbs like string trimmers? i looked a mine and don't see a similar set up, unless its below the primer bulb.


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## 140278

making this a sticky it's way to important to have get lost in time


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## 140278

rwh963 said:


> is there a screen like this hidden on small carbs like string trimmers? i looked a mine and don't see a similar set up, unless its below the primer bulb.


yes it's inside you have to take it apart to see it


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## Grunt

Cube carbs have a fine mesh screen recessed under the diaphragm side near the needle valve.


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## rwh963

Grunt said:


> Cube carbs have a fine mesh screen recessed under the diaphragm side near the needle valve.


more like "Borg" cubes!


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## orangputeh

i thought a guy was joking when he told me he had to remove engine to remove carb. never have done that with a Honda.

donyboy has 260,000 subscribers! man ol man


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## paulm12

so what brand/type engines have this filter/screen setup?


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## 140278

mtd's powermore for one. i'll check a loncin/toro carb in the am to see just so we know in the future 

wonder why they do that when the powermores have the screen built into the nipple plus have a well known shop poster add another in line unless it's to catch what comes loose inside the gas hose


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## ST1100A

The 'In-line' filters catch the bigger particles, where the tiny 'Mesh' type catch even finer smaller particles that get through an inline filter.


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## Tony-chicago

Must be trending cause I saw this video earlier today. I assumed my ignorance was unique. All carbs? Afraid to rip the inlet out, then not be able to reseal.
Great sticky!


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## ST1100A

Tony-chicago said:


> Must be trending cause I saw this video earlier today. I assumed my ignorance was unique. All carbs? Afraid to rip the inlet out, then not be able to reseal.
> Great sticky!


They're not all at the inlet, some are behind the float needle seat which is just down a little bit from the inlet, but close to it.


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## Elfiero

But, my carb has a cast in place fuel inlet- where is the "secret screen" hidden on this model?


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## JLawrence08648

The carbs that Dony was demonstrating was a Chinese carb, they have the hidden screen behind the inlet elbow. In the past I've been hesitant taking out the elbows because past they've been pressed in to aluminum, from Dony's video it seems with the Chinese carbs this is no problem.


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## tabora

Elfiero said:


> But, my carb has a cast in place fuel inlet- where is the "secret screen" hidden on this model?


Seriously? You asked this question without including your machine's model information?


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## RIT333

Come on tabora, don't you own a ouiji board, or are able to read minds be? LOL


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## orangputeh

tabora said:


> Seriously? You asked this question without including your machine's model information?


you are "all knowing" mistah taborah


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## paulm12

so why not just clean the carb with the ultrasonic then blow out the inlet from the seat area? Donyboy seemed reluctant on this. Or is the OEM screen not captured as well as his replacement one?

tx


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## tabora

paulm12 said:


> so why not just clean the carb with the ultrasonic then blow out the inlet from the seat area?


That's what I do. I just blast carb cleaner backwards through the needle seat.


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## orangputeh

paulm12 said:


> so why not just clean the carb with the ultrasonic then blow out the inlet from the seat area? Donyboy seemed reluctant on this. Or is the OEM screen not captured as well as his replacement one?
> 
> tx


thats what i do, i dont use china carbs for the most part. only Honda.


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## 140278

tabora said:


> That's what I do. I just blast carb cleaner backwards through the needle seat.


DITO! cleaner and air backwards, same affect , plus I'd also be afraid of a gas leak


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## paulm12

thanks guys, I thought maybe I was missing something.


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## cdestuck

My question here is what kind of screw or whatever did he take out to get the choke knob off the top of the long shaft. I can never make out how that knob comes off and end up yanking the whole shaft out of the carb and afraid sometime I’ll break something.


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## LouC

All of the Zama cube carbs on my Echo 2 stroke machines have screens in them even my Holley 4160 4bbl has a screen in the inlet. Perhaps this brings up the need for better fuel filters on these small engines. The Echos all have a replaceable filter in the tank and I never found crud in the screens of those carbs. My Toro has one of those small fuel filters (red ones) that is really just a screen but I have not had clogging problems on that carb either.


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## 140278

seems the real reason for this build up is simply old/bad gas , which returns us to only keeping what can be used in no more than 60 days and following the owners manual for long time storage


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## rwh963

LouC said:


> All of the Zama cube carbs on my Echo 2 stroke machines have screens in them even my Holley 4160 4bbl has a screen in the inlet. Perhaps this brings up the need for better fuel filters on these small engines. The Echos all have a replaceable filter in the tank and I never found crud in the screens of those carbs. My Toro has one of those small fuel filters (red ones) that is really just a screen but I have not had clogging problems on that carb either.


i have an echo 225 trimmer that was having starting issues. i removed the carb, took off the bottom silver bowl and side primer bulb. didn't see any screens. could you be more specific? it is the original carb. ended up purchasing a Hurtzl kit. like to get the OE carb working again.


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## 140278

2 stroke carbs are combo carbs, they function as both a carb and fuel pump in one. when they fail it is mostly from the membranes finger flaps getting hard and the fine screen inside the inlet section clogging up.


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## JLawrence08648

I've never seen a screen inside a 2 cycle carb, just the rubber pump diaphragm inside or a cloth type filter or screen in the tank.


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## tadawson

JLawrence08648 said:


> I've never seen a screen inside a 2 cycle carb, just the rubber pump diaphragm inside or a cloth type filter or screen in the tank.


I've rebuilt at least 3 Echo 2 cycle carbs (Zama carbs, actually), and every one has had a screen . . . frankly, never seen a 2 cycle carb that didn't from my view . . . Open it, take the pump diapragm out, and it's right there. Not in the inlet, but in the cross body passage from the pump side to the metering diaphragm/needle.



https://az417944.vo.msecnd.net/diagrams/manufacturer/green-machine/homelite/chain-saws/super-2-chain-saw-ut-10653/zama-carburetor/diagram.gif



Should be #5 . . .


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## Ziggy65

Follow up video from donyboy73:


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## Johner

captchas said:


> how many times have we had our members post about it? screws into the tank as the nipple
> View attachment 176768


Had one on a generator was not used for a long time the screen was gone, rotted away and jamming the shutoff . Cleaned and the screen came out as dust. Replaced now ok.


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## laser3kw

JLawrence08648 said:


> I've never seen a screen inside a 2 cycle carb, just the rubber pump diaphragm inside or a cloth type filter or screen in the tank.





tadawson said:


> I've rebuilt at least 3 Echo 2 cycle carbs (Zama carbs, actually), and every one has had a screen . . . frankly, never seen a 2 cycle carb that didn't from my view . . . Open it, take the pump diapragm out, and it's right there. Not in the inlet, but in the cross body passage from the pump side to the metering diaphragm/needle.
> 
> 
> 
> https://az417944.vo.msecnd.net/diagrams/manufacturer/green-machine/homelite/chain-saws/super-2-chain-saw-ut-10653/zama-carburetor/diagram.gif
> 
> 
> 
> Should be #5 . . .


My experience is closer to the second. The fine mesh screen is in the body. I find them with "hair" - a fine fiber-ish buildup. I think it is alien in nature.
As far as the screen mentioned in the video, I was thinking of maybe attaching a fuel or a safe liquid source to the inlet and observing the flow out the needle port as a possible check? Back-flushing it seems to be a good rebuild step for all carbs.


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## JLawrence08648

orangputeh said:


> i thought a guy was joking when he told me he had to remove engine to remove carb. never have done that with a Honda.


If you meant me, the engine is on a Homelite power washer and the tubular frame is blocking the removal of the carb, the carb can't be slid out, a poor design. At some point I'll sell it, it needs a new pump.


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## orangputeh

JLawrence08648 said:


> If you meant me, the engine is on a Homelite power washer and the tubular frame is blocking the removal of the carb, the carb can't be slid out, a poor design. At some point I'll sell it, it needs a new pump.


that is as bad as removing a subaru engine to replace $50 head gaskets. 
someone posted some other site that a certain Truck you have to remove transmission to replace starter. insanity.

that's why I like old cars and trucks. 12 year olds can work on them. 

even bicycles are insane now. around here they sell for $4000-8000 or more and you need special vocational training to repair them.
I had an old Peugeot that I bout new for $100 (in 1977) and rode it 5600 miles around the United States. Only thing I had to do was fix some flats and change the rear tire.

The world has become too complex if you let it. 

I have old cars, old snowblowers, old bicycle , old tools, old furniture, old appliances, old toaster , and an old wife.......


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## ChrisJ

I'm just over here cringing that he put that carb in the vice with the machined gasket surfaces against the steel jaws of the vice.

I understand there's a gasket but that was just wrong.


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## NOS

ST1100A said:


> Wow you can tell 'Donnyboy' is new at cleaning carburetors because almost every carburetor always had them there and that is the most common place for fuel line dirt to accumulate at.


Yes....
For a guy that fixes chain saws he also has never been shown how to tune and set up Tillotson carb.
There is another one called Chickanic who is quick on advice but real short on some things.

Maybe its partly coming from a lot of exposure to racing engines and hot saws but I just thought everyone at some point was aware of things like this tuning kit... ( McCulloch even had pne for the dealers at one time )


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## leonz

Tabora, is this part number 28 in the exploded parts diagram??


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## leonz

The tiny filter in the base of the fuel tank of my S620 Toro Snow Pup was what was plugged and the Dr. at the TORO SNOW PUP Hospital did not know it ever had a fuel filter in the base of the tank.

I tell a lot of people to install the RACOR fuel filters in thier sub compact and compact utility tractors to stop a lot of crap and ice from getting anywhere near the indirect injection pumps in their diesel engines as they have cheap 20 micron or greater filters.

RACOR offers a drop in 2 micron fuel filter cartridge for diesel fuel and kerosene fuel.

If I remember right the bulk motor fuels in Japan are filtered to that level.

RACOR also has a disposable spin on fuel canister for gasoline engines too which is the 120R-RAC01 model. These filters would be a very wise investment for large gas engines used on any zero turn lawnmowers as they use a filtered number of gallons to judge the life span of the filters.

These RACOR filters have a boss mating surface that requires an o-ring fitting-British Standard Pipe which provides easy adjustment and low torque tightening to seal it.

The way they work is water and heavy dirt falls out of the fuel as the fuel is centrifuged by the flow of the fuel through the fuel system. I really need to buy one of these for my truck. I have a 500 FG model for my home heating boiler but I cannot use it for gasoline fuel.


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## thool

I'd love to have someone analyze the gunk that came out. Is it material from the fuel line? Old insect parts? Some sort of varnish from bad gas?


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## Oneacer

Many tanks have a screen at the out-flow. ... that's why when having fuel issues, you always check the flow to the carb ... many times also, the line itself, or any shutoffs can go bad.


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## Mike in Mass

ST1100A said:


> They're not all at the inlet, some are behind the float needle seat which is just down a little bit from the inlet, but close to it.


Those you can see when you take apart the carb but the one behind the inlet fitting is stealth because I think of a pressed in (taper fit) part more like a "permanently assembled" item. Ignorance is bliss and I've been getting away with not knowing about it because I backward flush all vias with carb cleaner including from the main jet back out the inlet. So I've been unknowingly cleaning that screen all along! 😎


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## HillnGullyRider

The reason they put those screens in there is because they use cheap stamped steel tanks that aren't really meant for winter use where snow accumulates on top of fuel tanks. It's not just winter use either, anytime a piece of equipment is left-out overnight, where the temp drops below the dew point, causes condensation to form on the ceiling of steel tanks, this in turn forms water droplet's that when combined with gravity, end up in the bottom of your tank below the gasoline. Most of the time this h2o is so minute that is sucked into your carb and converted to steam during combustion, without you ever taking notice. Over time this condensate infiltration forms corrosion in your cheap stamped tank, and in your carby bowl. This in turn turns into the grit trapped by that screen. They don't trust Joe homeowner to add thier own fuel filter, so they hide one to keep it in place.

The same process is happening to your car's roof, underneath that headliner. 
Plastic tanks cure some of these ills, but h2o can still end up in your carb bowl , so it's best to remove and clean those at least twice a season, more if you run pump gas. 

This is at least one aspect where EFI is superior to carbs. However, anything mechanical involving liquid fuel, still needs scheduled maintenance attention and cleaning.


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## Mike in Mass

HillnGullyRider said:


> The reason they put those screens in there is because they use cheap stamped steel tanks that aren't really meant for winter use where snow accumulates on top of fuel tanks. It's not just winter use either, anytime a piece of equipment is left-out overnight, where the temp drops below the dew point, causes condensation to form on the ceiling of steel tanks, this in turn forms water droplet's that when combined with gravity, end up in the bottom of your tank below the gasoline. Most of the time this h2o is so minute that is sucked into your carb and converted to steam during combustion, without you ever taking notice. Over time this condensate infiltration forms corrosion in your cheap stamped tank, and in your carby bowl. This in turn turns into the grit trapped by that screen. They don't trust Joe homeowner to add thier own fuel filter, so they hide one to keep it in place.
> 
> The same process is happening to your car's roof, underneath that headliner.
> Plastic tanks cure some of these ills, but h2o can still end up in your carb bowl , so it's best to remove and clean those at least twice a season, more if you run pump gas.
> 
> This is at least one aspect where EFI is superior to carbs. However, anything mechanical involving liquid fuel, still needs scheduled maintenance attention and cleaning.


I guess I'm charmed. I've had my snowblower for 25 years and never had to clean the carb, (Tucumseh HMSK80 with a plastic tank). And I think the reason might be because, before I store it (in a shed) from ~April to December, I run the tank dry with some Marvel Mystery Oil mixed into the fuel. Someone told me long ago that it is a unique oil because it is less refined and has some paraffin left in it. So as the fuel and whatever else is in that oil evaporates, the paraffin remains on metal surfaces as a rust preventative. 
The problem of water contamination in gasoline is greatly reduced by the addition of oxygenated ethanol in E10 because the ethanol will absorb water .. up to a point. You probably won't get visible water at the bottom of a 1/2 tank of fresh E10 like you would with straight gasoline if left for a couple weeks with the cap off in a humid summer.


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