# TK carburetor problems



## DonTut (Aug 4, 2009)

I have an old Green Machine string trimmer (2000 Residential) with a TK carburetor. I have rebuilt the carburetor, cleaned the fuel system and checked the filter and lines. The trimmer will run as long as I depress the green primer button on the underside of the inlet diaphragm cover. Once it starts it spits fuel from the overflow pipe constantly but still won't run without priming. I read some discussion of the same problem on this site back in 2006 but no one seemed to solve the problem. I don't understand what that brass button under the inlet needle does or why it is there. I can move air through it in both directions and I have read in other forums that this may mean the carb body is shot. Does anyone have any insights that might help? Thank you.


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## 30yearTech (Sep 14, 2006)

That button is the tickler valve, when you push that button down, it opens a valve that lets the fuel run out the overflow pipe. If it's leaking then the metering chamber cannot pull enough vacuum to operate the metering diaphragm. The carburetor will always run lean. They are not (as far as I know) serviceable.


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## DonTut (Aug 4, 2009)

If the valve isn't servicable it would seem that the carburetor needs to be replaced. Is that correct? I haven't seen any vendors offering new TK carburetors. Can I use another brand that is more readily available?


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## 30yearTech (Sep 14, 2006)

What model Green Machine trimmer do you have. Do you know if it's a Mitsubishi engine? or a Zenoah?

I don't know if there are any other carburetors that will fit. TK Carburetors are kind of pricey but you should still be able to get one.


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## DonTut (Aug 4, 2009)

I have a model 2500 Residential. There is no serial number or other model number but there is a spot on the shaft where a label once was. The engine is a Zenoah (mine is spelled Xenoah with a stylized "o" with an "x" in its center), model G2A. I have the serial number if it makes a difference. You didn't mention anything but it seems that you think the carburetor can't be repaired. Is that a fair statement?


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## 30yearTech (Sep 14, 2006)

Well I am one of the first ones to never say never, but I honestly have not had much luck with the TK carburetors once they start leaking.

I always thought it was spelled with a "Z" oh well. The carburetor on a Shindaiwa T-25 trimmer should work for you. Take a look at this IPL for the carburetor, if I am not mistaken, Xenoah also made the engine for this particular model at least at one time.

Bad news is carburetor shows to sell for around $100.00. It might be money better invested in a new unit. You might try sealing off the tickler valve and see if you can get it to run that way. The only purpose of this set up, was to purge the carburetor, it was not needed for it to run.


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## DonTut (Aug 4, 2009)

I think you are right about a new trimmer. I may try to fool around with this one for awhile but I need to get some grass cut. Thank you for all your help.


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## Wotan (Sep 24, 2009)

*Gasket Set For TK carb*

Funnily enough today I received a gasket set for a TK carb fitted to a Zenoah engine. The gasket set included a rubber seal for the tickler that stopped the overflow. I think the thing is that you originally talked about is a button for fast running, that properly requires a new O ring. The set cost around £6.00 the O ring not included but you can buy them in Halfords if you what to buy the whole shop. Its a bit fiddly fitting as you have to be care full not to pinch the new o ring and sort of tease it in.


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## 30yearTech (Sep 14, 2006)

Wotan said:


> Funnily enough today I received a gasket set for a TK carb fitted to a Zenoah engine. The gasket set included a rubber seal for the tickler that stopped the overflow. I think the thing is that you originally talked about is a button for fast running, that properly requires a new O ring. The set cost around £6.00 the O ring not included but you can buy them in Halfords if you what to buy the whole shop. Its a bit fiddly fitting as you have to be care full not to pinch the new o ring and sort of tease it in.


Nope, the tickler valve in the TK carburetor is NOT serviceable, it's pressed in underneath the metering arm. The newer green machine units did not have the fuel cut off on the carburetor and used an ignition kill. Some of the TK carburetors had an O-ring seal to the discharge tube, with a little pin that sealed against it.


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## mudrat2 (Aug 27, 2019)

Not to open an old thread but put the information here for someone else looking for it.
You can pull the tickler valve out and replace the o-ring. The original o-ring seems to get eaten by ethanol.
Grip the brass pin and pull straight up. I used a small collet chuck used to hold small drill bits.
Replace o-ring and push straight back in.


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