Tecumseh mower leaking gas

Discussion in 'Shop Talk' started by WanderingOak, Nov 20, 2005.

  1. WanderingOak

    WanderingOak Well-Known Member

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    I have a Tecumseh mulching mower of uncertain vintage, and it is leaking gas like a sieve. It looks like the gas is coming out through the air intake. The entire tank drains out. I've been wondering why my shed had been smelling of gas the past few days, now I know. The motor is a MK IV, and I don't have the manual because it was a yard sale find. I am thinking it might be a gasket in the carburator. We did have a hard freeze a few nights ago, which may have caused problems. Does anybody know how difficult Tecumseh carbs are to rebuild? If it will cost more than $40 or so to fix it, I am thinking about buying a cheapie new one, even though it is late in the season. I use it for mulching leaves this time of year.
     
  2. Cabin Fever

    Cabin Fever Life NRA Member since 1976 Supporter

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    It's probably a soaked or leaking float in the carb. When this happens, the float sinks and the needle valve stays opens permanently which allows a continuous flow of gasoline into the carb.

    As gasoline fills the carb bowl, a functioning float will move upward and close the needle valve, thereby cutting off the flow of gasoline.

    The other possible problem is that the needle valve is not seating properly, which would also allow a continuous flow of gas into the carb. There may be a piece of crud in the seat of the needle valve. A cleaning should clear up that problem.

    I would take the carb off....remember how all the linkages and springs attach to it. Remove the carb bowl...be careful so the needle does not fall out. Spray all of the orifices and jets with carb cleaner. Spraying cleaner thru the gas inlet on the carb should do a good job of cleaning the needle valve orifice.

    Carefully remove the float The float actuates the needle valve. Do not loose the needle valve when you remove the float! Look at the float. If it is plastic, make sure that there is no gasoline inside of it. If the float is cork, make sure it's not "waterlogged" with gasoline.

    If the float is okay. Put it back, ensuring that it si attached to the needle valve. Put the bowl back on the carb and the carb back on the engine.
     

  3. moopups

    moopups In Remembrance

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    Check the float chamber vent, its a very small orface located at the top of the float chamber, about half of the size of a pencil lead's diameter. If it becomes clogged the gas will enter the chamber and compress the air until there is enough pressure to send the gas up the jet and out the air venturi. Have had this happen many times in the past. Spray WD-40 to see if the passage is open. Without visual proof this is inadequate as to cureing the problem.
     
  4. WanderingOak

    WanderingOak Well-Known Member

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    Thanks for the adivce. I'm not sure if I'll have much time to monkey with the old girl, so I might just take her by a small engine shop to see if they can do anything. I need a working mulcher, not a project. I should have mentioned that she was leaking as I was filling her with gas. I did not even attempt to start her, as I was not really in the mood for a major conflagiration.