Briggs & Stratton 17.5 HP engine stalling problems.

wornout4wd

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I have a Craftsman LAWN tractor MODEL 917.275371 with a Briggs & Stratton model 31C707-0230-E1
engine. It has been stalling out after running 10 minutes or so. I have done numerous remedies since the problem started. Drained Gas and refilled with fresh gas, replaced Spark plug, Replaced coil, all of which did not remedy the stalling problem. I have been all over the internet trying to find a solution to this problem and always find the same answers which I have implemented but to no avail. As a last result, I ordered a new carburetor with the new solenoid and installed it. Engine started fine, ran about 30 seconds then started missing and started blowing white smoke!! The Tractor is not that old, and up until the end of last season ran fine. Why would installing a new carburetor cause it to run worse than before and what could be causing it to start smoking where it never did that before?
 

SONOFADOCKER

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Smell the oil . Smell like gasoline ?
That tractor has a gravity feed carb . Add a fuel shut off and close it just prior to parking the tractor . Keep the carb empty when not in use .
I assume the carb needs another cleaning or rebuild .
 

wornout4wd

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Smell the oil . Smell like gasoline ?
That tractor has a gravity feed carb . Add a fuel shut off and close it just prior to parking the tractor . Keep the carb empty when not in use .
I assume the carb needs another cleaning or rebuild .

I smelled the oil dip stick and it does smell like gas. I just put a brand new Carburetor on it today, and thats when it started smoking for the first time. It ran great with the new carburetor for about 45 seconds.
 

SONOFADOCKER

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Danger danger ! The gasoline in the oil is burning . You can damage the engine . Change that oil and add the $2.00 fuel valve - weight of the fuel is pushing past the carb . Gallon of gas weights like 8 pounds ? A lot of force on the tiny carb.
 

wornout4wd

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Danger danger ! The gasoline in the oil is burning . You can damage the engine . Change that oil and add the $2.00 fuel valve - weight of the fuel is pushing past the carb . Gallon of gas weights like 8 pounds ? A lot of force on the tiny carb.

ok. Now I am confused. The carburetor I installed was an oem of the one that was on the mower. It has a fuel solenoid on the bottom of the bowl just like the carburetor I took off of the engine. I DID change the oil after I smelled the gas in it, thanks for that tip. After changing the oil, it ran like new with no further smoking problems. I cut grass with it for about 20 minutes. I cut the engine off acouple of times and restarted it with no problem. If the fuel valve is an issue, why wasn't it originally installed on the engine?? I'm just asking.
 

SONOFADOCKER

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The valve is a must with the ethanol gasoline and your gravity fuel delivery.
Even with stabyl in your fuel there will still be water in the gas. Water is heavier than gas. The water makes NO START problems .
Half machines have fuel pump. The others are gravity forced fuel .
Water WILL get into the carb bowl and make the jets weaken and open up. What happens is the gas passes from the carb to the valves . If the intake valve is open the crankcase fills with gasoline . If the exhaust valve is open the muffler fills with gas .....makes a BIG bang . When the oil is ruin you get the 18hp white fog machine .
I deal with about 2,500 machines over the year .
Full shut off gets added when ever there is room for it in the fuel line .
I have not had to touch a carb in my five tractors and four push mowers since adding the valve.
Just close the valve and let the carb run DRY .
Good luck .
 

wornout4wd

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The valve is a must with the ethanol gasoline and your gravity fuel delivery.
Even with stabyl in your fuel there will still be water in the gas. Water is heavier than gas. The water makes NO START problems .
Half machines have fuel pump. The others are gravity forced fuel .
Water WILL get into the carb bowl and make the jets weaken and open up. What happens is the gas passes from the carb to the valves . If the intake valve is open the crankcase fills with gasoline . If the exhaust valve is open the muffler fills with gas .....makes a BIG bang . When the oil is ruin you get the 18hp white fog machine .
I deal with about 2,500 machines over the year .
Full shut off gets added when ever there is room for it in the fuel line .
I have not had to touch a carb in my five tractors and four push mowers since adding the valve.
Just close the valve and let the carb run DRY .
Good luck .

Thanks...that makes sense. I will take your advice and put that valve on. I appreciate your input. Thanks again.
 
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