Chainsaw starting help.

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  #1  
Old 04-10-09, 04:38 PM
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Chainsaw starting help.

I am having a problem getting my chainsaw to run.

I have an old craftsman. I was using it fine last week. Today it will not run.

When I choke the carb is starts a little then shuts off as it always have. Usually I then turn the choke off and pull two times and it runs fine.

Now When I pull the cord it runs great for about 4 seconds. then it just turns off as if I hit the off switch. I think it is not getting gas. I took the fuel tube off and blew on it to see if I could blow bubbles into the gas tank. that tank must be well sealed as I pressurized it and gass started coming back out the tube into my mouth when I took a breath.

So I think the tube is clear. What I am wondering is how should the gas get from the tank to the carb. Is it a vacuum system. It seems as if the pull cord gets the gas into the carb but the running engine is not supplying what is needed to get the gas to the carb.

Any suggestsions?

Thanks

Dan.
 
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  #2  
Old 04-10-09, 06:24 PM
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Check to see if theres a screen over the muffler . alot of times they plug up with carbon, if not check restriction in the muffler itself. If it wont come apart we flambay them with an oxy/acetylene torch to burn out all the carbon build-up. Stinks though
 
  #3  
Old 04-10-09, 06:28 PM
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AAHHH thanks. kinda like a banana in the tail pipe.

I will look at it from this perspective.

one more thought however when I was playing with the gass idea--- I took off the gas line just after I turned off the choke and ran it for the 4 seconds and watched for fuel to come out of the gas line and none came out. So it sure seems like there is a lack of gas when running normally.

I will check the exhaust howerer.

Thanks

Dan .
 
  #4  
Old 04-10-09, 07:05 PM
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The carb pulls fuel through the line. Gas doesn't pump out of the tank if the line isn't connected to the fuel pump (which is in the carb). Sounds like you have either carb prob;ems or a crack or hole in the fuel line.
 
  #5  
Old 04-11-09, 07:16 AM
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I am thinking a crack in the line. that is what I am going after first. when I blow air into the gas tank with my mouth I can pressurize it and gas will return but I also read others post that said a crack they can barely see will make the carb suck air. So this all makes sense to me that there is a small crack in the line and is not big enough for all my hot air but big enough for the little has the carb needs. the line seems like it is old and hard due to age so a crack would make lots of sense.

Thanks for all your help.

Dan.
 
  #6  
Old 04-14-09, 06:11 AM
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Hey, Bruce here again, Dad just left for the hunting shack and his saw wouldnt run because of bad gas over 6 months and a plugged carb that was internally varnished. Most chainsaws run off vacuum created in the crankcase that pulsates the fuel pump diaphram in the carburetor. Agree with a possible cracked line or air leak. Ask the wife if you can pull er apart on the kitchen table, the chain saw that is. Im believing youll find the little carb diaphram has gotten rotten and will not pump the fuel required for normal operation.Again just trying to help.
 
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