11 HP Tecumseh 31" Snowthrower fuel problem

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  #1  
Old 09-11-08, 11:09 AM
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11 HP Tecumseh 31" Snowthrower fuel problem

Hi All

New to the group. My snow blower works perfectly on the first third of every tank of gas but quits and won't restart without topping up. Started in the 8th year of operation. Kind of has me puzzled?? Had thought of simply raising up the tank by 2/3s of it's heights to see if the problem goes away.

Anyone got any suggestions??

Thanks to all.
Bill

PS It just occurred to me that there may be a tiny break in the fuel line (perhaps near the primer) that breaks the syphon when it drops to the level of the break.

?????
 
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  #2  
Old 09-11-08, 12:27 PM
Join Date: Jan 2007
Location: MA
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Your fuel cap may not be venting, when it starts to die, loosen cap or with 1/2 tank of gas remove fuel line at carb and see if it drains into a clean bucket. If it is not draining loosen cap and see if you get flow. The reason it works with a full tank is there is no/little air in tank and when 1/3 is gone there is enough air to create a vacuum.
 
  #3  
Old 09-11-08, 02:05 PM
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Thank you

Yes, good idea, but I've already tried that with no success.

Do you think the idea of an air leak in the gas line could be the cause??

Bill
 
  #4  
Old 09-11-08, 06:18 PM
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If the fuel line had an actual leak, then the fuel would leak out of it, until it dropped below the level in the tank.

Does your unit have a fuel filter??

If it does, then perhaps it requires the extra force of the additional fuel to push through the filter.
 
  #5  
Old 09-11-08, 07:57 PM
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Hello again

No, there's no fuel filter.

I understand your point about leaking, but just the same I think there is an air leak in the primer somewhere that's breaking the syphon of gas to the carb.

Now ,, because the gas tank is above the carb, one would tend to believe that it's a straight gravity feed and in fact it is a straight gravity feed until the level of fuel in the tank is reduced about two inches to a point where the level of the fuel in the tank equals the level of the primer. Once the fuel level in the tank drops below the level of the primer there is no reason for the fuel to climb up to the level of the primer and on to the carb unless the weight of the fuel in the line between the primer and the carb is allowed to pull (suck) the fuel from the tank up and over the primer which is the high point in the gas line.

So far as leaking, Iím not sure how the primer is constructed but I can imagine a situation where a small hole might not allow fuel under almost no pressure to leak out while, at the same time being able to allow air in the line. All that it would take would be break, such as to form, in essence, a flap. Not unlike a one way leather flap valve. For that matter, there may well be something in the construction of the primer that when combined with some form of fault or failure it may well allow no fuel leakage while allowing air in to break the syphon.

I honestly have no idea if this hypothesis is sound or not but I can think of no other explanation for what I am seeing.

Thanks again for exchanging your thoughts
 
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