another trimmer to throw away

[38racing]

So I went in. I did not find the ethanol jelly I expected. The carb looked clean inside. I put it back together and get same result. So I took it apart again , mainly to compare gaskets and diaphragms with picture of a walbro wyl kit. This time I analyzed the fuel flow path. I got to a point where I think there should be flow but there is not. My images are blurry but hopefully you can see what I have.
The first picture is the metering well. Fuel gets to it when the needle on the right opens. There is the hole in the bottom of the well which I assume is the exit point of the fuel to the main jet. There is also a hole , not visible, in the side which leads to the primer bulb circuit.
The second picture is the other side of that body piece. The brass piece on right is the needle seat where fuel goes up into metering well. On the right that brass piece with cross opening is directly below the hole in the metering well. When that body piece is mounted to main carb body it lines up and touches the bottom of the main jet.
So, to me, there should be free fuel flow from the metering well through small hole and cross opening to get to main jet. But if I spray carb cleaner into the well it just sits there and does not run out. And pressure spraying either side gets no flow. Should I find my misplaced dental pick and just poke through it? Maybe my ethanol jelly is in that passage?
http://web.ncf.ca/da229/smallengine/huayi-carb1.jpg
http://web.ncf.ca/da229/smallengine/huayi-carb2.jpg

[bgsengine]

Pull the filter screen and check the back side of it -- that's where they get plugged up, not on the visible side like most cube carbs you may be used to.

[38racing]

Pull the filter screen and check the back side of it -- that's where they get plugged up, not on the visible side like most cube carbs you may be used to.

Can double check it but I think I tested that fuel was going through it.

[Deere2me]

So I went in. I did not find the ethanol jelly I expected. The carb looked clean inside. I put it back together and get same result. So I took it apart again , mainly to compare gaskets and diaphragms with picture of a walbro wyl kit. This time I analyzed the fuel flow path. I got to a point where I think there should be flow but there is not. My images are blurry but hopefully you can see what I have.
The first picture is the metering well. Fuel gets to it when the needle on the right opens. There is the hole in the bottom of the well which I assume is the exit point of the fuel to the main jet. There is also a hole , not visible, in the side which leads to the primer bulb circuit.
The second picture is the other side of that body piece. The brass piece on right is the needle seat where fuel goes up into metering well. On the right that brass piece with cross opening is directly below the hole in the metering well. When that body piece is mounted to main carb body it lines up and touches the bottom of the main jet.
So, to me, there should be free fuel flow from the metering well through small hole and cross opening to get to main jet. But if I spray carb cleaner into the well it just sits there and does not run out. And pressure spraying either side gets no flow. Should I find my misplaced dental pick and just poke through it? Maybe my ethanol jelly is in that passage?
http://web.ncf.ca/da229/smallengine/huayi-carb1.jpg
http://web.ncf.ca/da229/smallengine/huayi-carb2.jpg

" Brass piece" , really? THAT is a NON REPLACEABLE check valve!! Did you test it? I didn't think so. If it ain't workin' toss the freakin' carb/ unit and move on! You need to get a BASIC handle on the workings of a cube carb. Walbro and Zama both have good explanations on their site. This site has good info, especially if yer just startin' out or are new to small engines: http://outdoorpowerinfo.com/repairs/walbro_WT340_carb.asp Not the exact same carb, but the check valve is clearly shown!

[38racing]

So I went in. I did not find the ethanol jelly I expected. The carb looked clean inside. I put it back together and get same result. So I took it apart again , mainly to compare gaskets and diaphragms with picture of a walbro wyl kit. This time I analyzed the fuel flow path. I got to a point where I think there should be flow but there is not. My images are blurry but hopefully you can see what I have.
The first picture is the metering well. Fuel gets to it when the needle on the right opens. There is the hole in the bottom of the well which I assume is the exit point of the fuel to the main jet. There is also a hole , not visible, in the side which leads to the primer bulb circuit.
The second picture is the other side of that body piece. The brass piece on right is the needle seat where fuel goes up into metering well. On the right that brass piece with cross opening is directly below the hole in the metering well. When that body piece is mounted to main carb body it lines up and touches the bottom of the main jet.
So, to me, there should be free fuel flow from the metering well through small hole and cross opening to get to main jet. But if I spray carb cleaner into the well it just sits there and does not run out. And pressure spraying either side gets no flow. Should I find my misplaced dental pick and just poke through it? Maybe my ethanol jelly is in that passage?
http://web.ncf.ca/da229/smallengine/huayi-carb1.jpg
http://web.ncf.ca/da229/smallengine/huayi-carb2.jpg

" Brass piece" , really? THAT is a NON REPLACEABLE check valve!! Did you test it? I didn't think so. If it ain't workin' toss the freakin' carb/ unit and move on! You need to get a BASIC handle on the workings of a cube carb. Walbro and Zama both have good explanations on their site. This site has good info, especially if yer just startin' out or are new to small engines: http://outdoorpowerinfo.com/repairs/walbro_WT340_carb.asp Not the exact same carb, but the check valve is clearly shown!

actually I viewed a couple videos (one from walbro) and a walbro tech item on this specific model. And I have worked on trimmer carbs before. None of those identified that piece as a check valve and certainly did not make any reference to testing it. I may be wrong (I expect you will point that out) but this piece is in the rotary carbs and not the butterfly carbs.

[Deere2me]

actually I viewed a couple videos (one from walbro) and a walbro tech item on this specific model. And I have worked on trimmer carbs before. None of those identified that piece as a check valve and certainly did not make any reference to testing it. I may be wrong (I expect you will point that out) but this piece is in the rotary carbs and not the butterfly carbs.

Look, I'm not out to prove you wrong, I'm here to help educate ! Well...maybe agitate a little too, to lighten things up a bit!
Forget about the u toob vids, most of them morons ain't got a clue! Most don't mention the check valve , 'cause they don't know WTF it is! PLus you can't do much about it since it is non replaceable. But with your carb you CAN replace the pump body assy. that the valve is part of. Prolly ain't worth it, though.
You say you've worked on trimmer carbs before, well just about all of em have those pressed in non removeable check valves!
Since I'm in a good mood, I'm gonna tell ya how to check the check valves ( though it is explained in one of them sites). Get ya a short length of tygon tubing with an OD that will cover the brass part. Cut one end perfectly square. Stick that end on the check valve and GENTLY blow or suck. You should be able to pass air in only one direction, depending on which way the valve is pressed in. Some all ya see is a round brass bullseye with a hole in it, those should allow a blow to pass. Others ya see a brass slug with a cross or staking in the brass ( like what you got), those should only allow a suck to pass. Passing gas both ways and it's trash! I have a couple diff. dia. tubes that I mark on the square end in my "carb kit". You can also use the method on the Needle valve passages, just unscrew the needle/s.
Link us up to that Walbro vid.

[KE4AVB]

38, I got a question here. I read thru this thread and I am wondering has this ever hit when manual fed fuel?

The reason is I just got in one of those Troy-bilt TB22 (Craftsman) trimmers that would not start. After going thru it I found that one of cylinder bolt was broke off and the other mounting ear broken too which why it would not start. Fustrating that all they sell is the short block and all I needed was the cylinder.

Now if the you need any pictures of that WT 973 (753-06190) carburetor, this unit has one on it but is not the same as that current carburetor you got. I would thick the hook-up will be different.

[38racing]

38, I got a question here. I read thru this thread and I am wondering has this ever hit when manual fed fuel?

The reason is I just got in one of those Troy-bilt TB22 (Craftsman) trimmers that would not start. After going thru it I found that one of cylinder bolt was broke off and the other mounting ear broken too which why it would not start. Fustrating that all they sell is the short block and all I needed was the cylinder.

Now if the you need any pictures of that WT 973 (753-06190) carburetor, this unit has one on it but is not the same as that current carburetor you got. I would thick the hook-up will be different.

It fires on carb cleaner put into the air intake and fuel gets picked up and returned to tank with the primer so I conclude fuel is just not making it to the main jet (no separate idle jet that I see on the rotary design, my research indicates the internal needle just limits fuel from main jet to control idle) or it is getting no pulse. Since the trimmer is new last year I don't know why the pulse would not be there. I am going to check for pulse (as per Walbro , non Utube) video. Will also pay close attention to the walbro video re- that check valve. I have pic of the wt-973 as it's the butterfly style so the throttle wire hookup is different.

[38racing]

ok , looking closer at a Walbro manual I see that check valve before the main nozzle. It says it is only necessary in the barrel design to prevent air coming from main nozzle during the air purge. But in their (walbro) video they fail to make any reference to it in the disassembly/cleaning/testing or assembly of the rotary design. So since I assume that fuel should flow through it and does not that I will maybe try a cheap china carb just to see if it will run again.

[Deere2me]

ok , looking closer at a Walbro manual I see that check valve before the main nozzle. It says it is only necessary in the barrel design to prevent air coming from main nozzle during the air purge. But in their (walbro) video they fail to make any reference to it in the disassembly/cleaning/testing or assembly of the rotary design. So since I assume that fuel should flow through it and does not that I will maybe try a cheap china carb just to see if it will run again.

Actually, they DO mention the check valve at 14:31 or thereabouts, but they don't point it out, nor do they give any explanation of it's function!. It is also clearly shown at several points , 14:12, 16.53, and again at 18:18, but again, they fail to point it out and no explanation. Overall it's a pretty piss poor video coming from an OEM. I'm not the least bit impressed.
But it does give a somewhat BASIC understanding of the carbs.
Here's the link to the Walbro video: http://www.youtube.com/watch?v=cDaOcNrS6BM&feature=youtu.be