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Discussion Starter #1
I'm working on a 5 horsepower Briggs & Stratton engine. With a standard small engine carburetor I replaced my needle and seat with part number 39818 8 It seems to work fine with the bowl off. When I hold the carburetor as it would be on the engine. The needle drops down and I can blow air through. When I tilt it upside down. The float goes up and shuts off the air flow. However When I put the bowl on the carburetor. The bulb shuts off the air flow and I can't blow any air through. The gas line Does anyone know what the problem is?
 

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You need to adjust the float. With the carb upside down the float should set level with the bowl flange. You will have to bend the float arm to make that adjustment. There is a little prong on the on the back of the float arm to set the float depth in the bowl. Without the proper dimension it can be set just high enough to keep the float from contacting the bowl and get by.
 

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Discussion Starter #3
Thanks for your quick response, Are you speaking about that little piece of plastic? That the needle sets down on As shown in the picture with the pinpoint touching it. ? And if so how do you bend it?
 

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Discussion Starter #7
The picture is a little blurred ...so hard to tell...buA]
Yes, I will try bending That little piece of plastic up words. And hopefully that will let the floats. Set down lower. In the bowl Thank you. I appreciate it.
 

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Before you bend the tab on a plastic float, be aware they can and will break... If you use a heating device, such as a screwdriver(chisel, nail, ???) stuck into a hot flame, you may have better luck modifying the float level without breaking the tab. The heat should be applied to make the plastic pliable, and then you can move it, hold it in its new place, let it cool, and it will likely stay where you put it.
Be aware that most times those floats are so precise they do not need any adjustment, and doing an adjustment is not a 'factory approved' solution. Generally, if a plastic float is 'off', something else is worn, such as the needle, seat, float pivot pin, or the 'hinge' section of the float itself. If you had water in the gas, and it was left in the float bowl over winter, and froze, I suppose it could 'modify' the float setting, but more liklely it would have cracked the plastic and you'd have a 'sink' instead of 'float'.
When you put the bowl on the carb, it may be that the float is getting pushed upward by the float bowl, or a ridge/bump in the float bowl, and closing the needle valve. Generally, you should not have to touch the float to make it work. You may have gotten the wrong float for your carb. Is it the same as the original you are replacing? Is it possible that the needle retaining 'spring'(springy metal) is out of position?
When you hold the carb inverted so the float weight is closing the needle to the seat, blocking airflow, does the float body(roundy tubular part) appear to be roughly parallel to the gasket surface where the float bowl would seal? The float should be roughly horizontal when the carb is inverted. If it is too high, as in the float is riding at an angle, high on the end away from the pivot, I would inspect closely the needle fitting, the retainer, hinge, etc, and also compare those bits to the old one. There should be very little variance, almost to the point of being so minor that it cannot be measured, between old and new when installed in place.
Be careful if you do some melty work, as for sure you are making the parts non-returnable if you modify them.
Some have used a Bic type butane lighter to heat up a metal implement to soften the float tab material, FWIW.
tom
 

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Discussion Starter #10
Before you bend the tab on a plastic float, be aware they can and will break... If you use a heating device, such as a screwdriver(chisel, nail, ???) stuck into a hot flame, you may have better luck modifying the float level without breaking the tab. The heat should be applied to make the plastic pliable, and then you can move it, hold it in its new place, let it cool, and it will likely stay where you put it.
Be aware that most times those floats are so precise they do not need any adjustment, and doing an adjustment is not a 'factory approved' solution. Generally, if a plastic float is 'off', something else is worn, such as the needle, seat, float pivot pin, or the 'hinge' section of the float itself. If you had water in the gas, and it was left in the float bowl over winter, and froze, I suppose it could 'modify' the float setting, but more liklely it would have cracked the plastic and you'd have a 'sink' instead of 'float'.
When you put the bowl on the carb, it may be that the float is getting pushed upward by the float bowl, or a ridge/bump in the float bowl, and closing the needle valve. Generally, you should not have to touch the float to make it work. You may have gotten the wrong float for your carb. Is it the same as the original you are replacing? Is it possible that the needle retaining 'spring'(springy metal) is out of position?
When you hold the carb inverted so the float weight is closing the needle to the seat, blocking airflow, does the float body(roundy tubular part) appear to be roughly parallel to the gasket surface where the float bowl would seal? The float should be roughly horizontal when the carb is inverted. If it is too high, as in the float is riding at an angle, high on the end away from the pivot, I would inspect closely the needle fitting, the retainer, hinge, etc, and also compare those bits to the old one. There should be very little variance, almost to the point of being so minor that it cannot be measured, between old and new when installed in place.
Be careful if you do some melty work, as for sure you are making the parts non-returnable if you modify them.
Some have used a Bic type butane lighter to heat up a metal implement to soften the float tab material, FWIW.
tom
 

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Discussion Starter #11
Thank you for all the information. It was very helpful. I did solve my problem by warming up the little piece of plastic. And bending it up just a hair. I use my heat gun just to warm it because I didn't want to break it. I did replace the needle and seat with a new one. Although I did not replace the float. But you were correct. It is just a minor adjustment the first time I bent it I bent
  • at way too much and it left the gas flow out the bowl of the carburetor. So I remove the carburetor and took it apart again and ben n it back to where it was before I thought but I must have got it right back great because it's working perfectly now. I do appreciate all of this information. He saved me a trip to the repair shop all you guys. As always thank you very much.Jim
  • Before you bend the tab on a plastic float, be aware they can and will break... If you use a heating device, such as a screwdriver(chisel, nail, ???) stuck into a hot flame, you may have better luck modifying the float level without breaking the tab. The heat should be applied to make the plastic pliable, and then you can move it, hold it in its new place, let it cool, and it will likely stay where you put it.
    Be aware that most times those floats are so precise they do not need any adjustment, and doing an adjustment is not a 'factory approved' solution. Generally, if a plastic float is 'off', something else is worn, such as the needle, seat, float pivot pin, or the 'hinge' section of the float itself. If you had water in the gas, and it was left in the float bowl over winter, and froze, I suppose it could 'modify' the float setting, but more liklely it would have cracked the plastic and you'd have a 'sink' instead of 'float'.
    When you put the bowl on the carb, it may be that the float is getting pushed upward by the float bowl, or a ridge/bump in the float bowl, and closing the needle valve. Generally, you should not have to touch the float to make it work. You may have gotten the wrong float for your carb. Is it the same as the original you are replacing? Is it possible that the needle retaining 'spring'(springy metal) is out of position?
    When you hold the carb inverted so the float weight is closing the needle to the seat, blocking airflow, does the float body(roundy tubular part) appear to be roughly parallel to the gasket surface where the float bowl would seal? The float should be roughly horizontal when the carb is inverted. If it is too high, as in the float is riding at an angle, high on the end away from the pivot, I would inspect closely the needle fitting, the retainer, hinge, etc, and also compare those bits to the old one. There should be very little variance, almost to the point of being so minor that it cannot be measured, between old and new when installed in place.
    Be careful if you do some melty work, as for sure you are making the parts non-returnable if you modify them.
    Some have used a Bic type butane lighter to heat up a metal implement to soften the float tab material, FWIW.
    tom
 
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