Chainsaw carb spitting fuel

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  #1  
Old 10-28-05, 05:15 PM
roofgunner
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Chainsaw carb spitting fuel

I have a Craftsman chainsaw that is spitting excess fuel out the carb while running. I rebuilt the Walbro carb and that didn't help. The saw runs fine with the aircleaner cover off but when it's put on there is enough excess fuel spitting inside that causes an over rich mixture to evently stop the saw. The air filter is clean. The saw runs well with lots of power but only with the cover off. Everything is clean and blown out. I'm wondering if the reed valve has a problem. Any ideas?? Tom
 
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  #2  
Old 10-29-05, 12:09 AM
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Yes, if it has a reed valve it is probably the problem.
 
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Old 10-29-05, 05:55 AM
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It is rare for modern saws to have reed valve intake unless you have a higher end saw. On your Craftsman, it is most likely piston port. What is the model number of your saw? If, in fact, you have a piston port intake design then (and actually in either case) you will want to check the exhaust port for carbon build-up. I'm sure you will find it to be nearly closed up thereby creating excessive back pressure and thus spit fuel out the carburetor.
 
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Old 10-29-05, 07:59 PM
roofgunner
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I'll check the exhaust port.

Thanks for the response. I thought of the exhaust valve port, and the reed valve. I believe it does have a reed valve as when I removed the carb, I think I did see a reed valve. I talked with a mechanic at a Stihl shop and he said that the spitting is typical and that the Craftsman is a lower end saw. However, I agree it is, but it couldn't have run this way from the factory. I'll check the exhaust port. I agree with your diagnosis and I'll check it. The saw was given to me and I don't really want to put any money in to it as I have have a Stihl 009l. a Huskey 36 and Huskey 55 all that run great. Thanks all! I've run Amsoil 100 to 1 mix for years in my equipment and have not had problems with carbon build up but with this saw I think the owner used regular 2 stroke oil.
 
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Old 10-30-05, 04:19 PM
roofgunner
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It Seems the problem is solved!

I cleaned the exhaust port which was carbonized. Also I made a gasket out of metal that was missing between the muffler and port. That didn't solve the problem. Then I removed the carb, and got into the reed valve, which consisted if a trianguler valve. Somehow saw dust held together with oil, etc. had got between the assembly and valve so that it would not close all the way. I checked the seals, and cleaned everything, put it back together and so far the saw runs normally and does not spit fuel. Thanks for the help. I worked for Kawasaki as a mechanic and the reed valve in this instance is a very simple one compared to a motorcycle two stroke motor.
 
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Old 10-30-05, 07:53 PM
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Great! It is a very simple and kinda cheaply made valve, but it works just the same. Glad you got it fixed!
 
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