Tecumseh 3.5 starts but runs only a few seconds

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  #1  
Old 10-11-06, 06:31 PM
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Question Tecumseh 3.5 starts but runs only a few seconds

I recently reassembled a 3.5hp tecumseh with no ajustment on carburator. The engine starts but runs only a few seconds and sometimes do a backfire when dying. I thoroughly cleaned all holes in the carburator, float bowl fastener main hole and idle hole with no success after reading similar problems on this site. I tried without gas tank cap to make sure it breathe properly without success again. What else may I check? Can it be related to ignition?

Thanks in advance
 
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Old 10-11-06, 07:04 PM
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It sounds like it is still a carburetor related problem. If you could post the model number off of the engine, I could get a better idea of which carburetor you have and some ideas of things too look for.
 
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Old 10-11-06, 07:22 PM
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Thanks a lot for taking time. The engine model number is
TVS90 43704L (C)
 
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Old 10-12-06, 01:29 AM
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Did you find and clean the very tiny hole near the end of the bowl screw in the un-threaded section? It can be quite hard to see, especially if it's clogged. You may also need to replace the nozzle O-rings.
 
  #5  
Old 10-12-06, 06:46 AM
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After looking at a parts breakdown on your unit.
Check to make sure you are getting fuel into the float bowl.

Double check the nozzle (tube that extends up into the throat of the carburetor directly above the nut that holds the float bowl on) make sure it is open and has no build up in it.

Check the primer bulb on the side of the carburetor, make sure there are no holes or tears in it. If any air can get by the primer then fuel will not draw properly through the nozzle.

Make sure you have a good seal between the carburetor and intake manifold as well as the manifold to engine block.

Let us know what you find.
 
  #6  
Old 10-13-06, 04:48 PM
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Smile Guess what...

Thanks for your advices. I was convinced that the carb was perfectly clean, and I was reluctant to open it a fourth time. I realized that the symptoms were similar to my snowmobile when it needs new spark plugs... A new spark plug and it runs like a new.

Thanks again.
 
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Old 10-15-06, 12:06 PM
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thats sure interesting

good thread here good info
 
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