# Walbro Carb issue



## Alex9 (Jan 14, 2016)

*Rebuilt Chainsaw Stalling*

Hi, I'm trying to get my Echo cs 310 chainsaw going after sitting a couple years or so. It has a Walbro WT-246 Carburetor.

What I've done:
-Replaced all fuel lines
-Replaced fuel filter
-Rebuilt carburetor
-Replaced with fresh gas
-"cleaned" the spark plug

Someone mentioned the check valve nozzle so I inspected it and there was something sticking out of the little brass nozzle that sticks out inside the carb body and I managed to pull it out. It's a little rubber disc. Later on I read somewhere that compressed air shouldn't be used as it could dislodge parts and I did use compressed air . I got impatient and just stuck the rubber disc mentioned above into the hole in the check valve (where I think it came from) hoping it would set itself flat. 

I can't seem to find the part number for the check valve assembly but someone said it can be removed by twisting a screw into it but then it would have to be replaced.

It starts with the choke a little open and accelerates really high when I open the choke fully or when I give it more than a little gas. So I am able to give it gas and it revs like crazy but stalls if I give it full gas(air). I hope that makes sense to someone.

There's a couple pictures in the "My Photos" link


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## paulr44 (Oct 14, 2008)

Your carb. IPL is here:

http://wem.walbro.com/walbro/product2.asp?partnum=WT-246-1&Series=WT

They don't show a check valve available as a brass insert (cartridge type). What it appears to have is the circlip retained check valve disk or screen. These are replaceable too, and usually come with the rebuild kit (K20-WAT) including the (expletive omitted) circlip.

Walbro uses 2 types of check valves, one is a neoprene or nitrile type disk, the other is a capillary screen (read their service manuals for theory, they're free to download).

The disk type is often in a non-serviceable cartridge, and usually (but not always) available as a replaceable item, which you would usually push out from the chamber side into the venturi, and simply press the new one in.

The capillary screen type requires a bit more finesse, given it's minute size. The circlips are near impossible to remove without buggering up the carb. body a bit.

Hope this helps.


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## paulr44 (Oct 14, 2008)

P.S. I just looked at your pics...I think you will probably need a new carb. Email Walbro, Luis will probably reply - he's excellent and head of aftermarket.
And as for servicing any diaphragm type carbs....Never use high-pressure air in the check valve areas, better yet, don't use high pressure at all. Never use xylene carb. cleaners as it can deform (curl) check valves.


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## Alex9 (Jan 14, 2016)

Dang. I really thought I did my research before rebuilding but not enough . Thanks for taking the time.


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## Alex9 (Jan 14, 2016)

Correction. It's a wt-946, no 246. Sorry about that, but does that change anything?


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## paulr44 (Oct 14, 2008)

Yes, everything. The 946 isn't listed on Walbro's site, and Echo doesn't show a nozzle but the 996 on Walbro's does show a replaceable nozzle.

So, call or email Walbro and ask them for the part number for the nozzle, and order it from a local dealer or online.
[email protected]
1-989-872-7322

However, the symptom you're describing usually isn't associated with a bad high-speed nozzle check valve. The check valve prevents air from purging the fuel out of the metering chamber at low/part throttle.

A whole new carb. isn't very expensive either. Perhaps you have a local dealer on the island?


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## Alex9 (Jan 14, 2016)

Thank you


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