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tecumseh 6.75 gas leak


vandolizm's Avatar
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Join Date: Mar 2008
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TX

03-04-08, 08:02 AM   #1  
tecumseh 6.75 gas leak

I have a Sears lawnmower with a tecumseh engine model # 143.016708. I recently lost the idle mixture screw (part # 640027), it loosened and fell out. I replace it. But gas is leaking from the screw. All the gas is drained out of the tank through the screw. Why is gas leaking from the idle mixture screw and how can I stop it from leaking.

 
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smallengineguy's Avatar
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03-04-08, 08:23 AM   #2  
You may have a leak in your float. Remove float and shake to see if their is gas in there. Replace float if there is. While in the carb, replace the needle and seat and be sure float level is adjusted correctly.

 
vandolizm's Avatar
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03-05-08, 07:25 AM   #3  
There is nothing in the float. Do I still need to replace it, along with the needle and seat? Should I also replace the bowl, gasket, and bolt? Or is cleaning it enough?
Thanks so much for your help.

 
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03-05-08, 07:47 AM   #4  
You said you lost the screw and you replaced it and the fuel is leaking out of the carb. You did not say that you also replaced the o-ring seal, washer and spring that applies tension on the screw so it will not vibrate out. Make sure you have replace all the missing parts as shown in the diagram on the Sears site for the carb.

 
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03-05-08, 08:13 AM   #5  
I replace the idle restrictor screw part number 640027. Does this screw have an o-ring and spring tensioner also?

 
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03-06-08, 07:15 AM   #6  
I see in the parts that the idle restrictor screw does not have a o-ring and spring since it is actually a fixed jet carb. This screw is not adjustable and is set snug. I would suggest you remove the carb and replace the needle valve and seat. Make sure the new seat is installed with the two ring side into the carb body first as this is the seal side of the seat. Do you have a metal float or plastic? The new replacement floats are plastic. When you reinstall the float and needle valve check with vacuum on the fuel inlet that the needle valve seats and will shut off the fuel flow. Some times corrosion will made the seat not seal and will weep around it.

 
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03-06-08, 08:14 AM   #7  
I will replace the needle, seat, and clip and hopefully it will stop leaking.
This is a great website and help forum.
Thank you "smallengineguy" and "camino kid" for all your help.

 
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