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Replaced needle and seat and still leaking


pmart60's Avatar
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01-22-14, 04:54 AM   #1  
Replaced needle and seat and still leaking

I have a Tecumseh 8 Hp engine on an Ariens Snowthrower. I picked the blower up for nothing and it was in decent shape so I went to work getting it up and running. When I got it running I had to shut it down because the carb was overflowing. I immediately suspected the needle and seat so I replaced both. I put it back together and to my dismay, it is still leaking as soon as the bowl fills with gas. I believe it still has something to do with the needle and seat but seeing as they are new, I'm a bit mystified. Anyone have any ideas?

Thanks

Paul

 
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01-22-14, 05:21 AM   #2  
100 % sure the float bowl is not leaking and is filled with gas?
You did install the little clip that attaches the needle valve to the float? (some just slide into a slot in the float valve)

 
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01-22-14, 06:33 AM   #3  
Does your bowl have a bolt through the center bottom? There is a gasket under the head of the bolt that might need replacing. If it's leaking around the top of the bowl the gasket there may need replacing.

Like Joe mentioned. Attaching the needle to the float and getting it installed properly can be a bit fidgety. Also make sure that you have the bowl rotated properly. The bowl may have a high and low side when looking at the bottom. You want the low, deeper part away from the float's hinge to allow room for the float to move. If rotated incorrectly the float may hit the bottom of the bowl.

 
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01-22-14, 06:33 AM   #4  
Sounds like you will need to remove the carb and look at that needle and seat a little closer. When you remove it, and every time you go to reinstall the carb, you can put your lips on the fuel input nipple and blow some air into the carb. Since the carb is empty, when the carb is in its proper orientation, air should flow freely. Now turn the carb upside down and blow air again. The air should be restricted, since the weight of the float should push the inlet needle into the seat. If the air is not restricted, it is going to leak fuel when reinstalled. This little test can be done without the carb bowl on it as well.

 
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01-22-14, 07:34 AM   #5  
It could be that the atmospheric vent is blocked look here:


 
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01-22-14, 09:07 AM   #6  
Perhaps you could give us a better description of where you are seeing the leak. I thought is was out the carb throat, etc., but you said that you had to shut it down. I imagine if it was leaking into the carb throat the flooding would have shut it down for you.

In any event, let us know where the leak is and perhaps we can give you better suggestions.

 
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01-22-14, 10:46 AM   #7  
Did you also replace the float?


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01-25-14, 07:58 AM   #8  
After checking all the above,they fail to mention that the seat only goes one way.There is a smooth side and the other side has a ridge or groove in it.The smooth side goes up where the needle sits on. Hope this helps

Jerry

 
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01-25-14, 08:06 AM   #9  
And has the float been adjusted? Could be a bent tang. If so, the needle won't seal shut when the float rises to it's maximum height.

 
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01-25-14, 08:57 AM   #10  
So jsouth the needle seats on the smooth side?


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01-26-14, 04:17 PM   #11  
thanks pilot for your response. Both gaskets you speak of came with the needle and seat kit. The bowl is oriented properly but even if it was not, the float not dropping all the way would not be the problem because it is when the float is in its upper most position (bowl filled) that the needle seals into the seat preventing the flow of gas into the bowl. I haven't had a chance to investigate further since my initial post but I will definitely post my findings.

Paul

 
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01-26-14, 04:22 PM   #12  
according to the service manual, the float, when properly adjusted, should be parallel with the carburetor body and it is

 
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01-26-14, 04:27 PM   #13  
no i did not replace the float but it is the next thing I will take a look at. It may have a hole and is leaking but I don't think so. The carb starts overflowing quickly after I turn on the gas flow from the tank, I would suspect that if the float had a pin hole, it would at least float initially to shut off the flow of gas at the needle and seat. It seems to flood too quickly for it to be the float, but I will be checking that as well when I get a chance to pull it apart again.

 
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01-26-14, 04:30 PM   #14  
thanks jerry. I will take a look at that. If I remember correctly, the seat has a tapered side and a flat side. I believe I installed it with the tapered side facing the needle so the needle would fit into the taper.

 
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01-26-14, 04:36 PM   #15  
Thanks OptsyEagle, I will give this a try. The other thing I plan on doing is after removing the carb, I will take off the bowl, attach the fuel line and manually operate the float to see if when it is in the upper most position, the fuel flow stops. This should tell me if the needle and seat are working correctly. I will try your suggestion of blowing air into it first (a bit less of a mess).

 
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02-24-14, 09:19 AM   #16  
Hi all,

Thanks to all who posted replies to assist me on this. It has been a while but I finally found some time to get back to this project (I have way too many going on). I was able with out much trouble to pin it down to the float as some of you had suggested. I removed the fuel tank, and connected a fuel line to it on the work bench. I removed the bowl and lightly pressed on the float so that the needle was seated and opened the fuel petcock. The needle and seat worked fine. I made sure the float was properly adjusted and put the bowl back on. I opened the petcock and within 20-30 seconds, fuel was again overflowing from the carb throat and the vent hole. I figured that it had to be the float so I removed the bowl, removed the float and dried it off. I shook the float and sure enough it had fuel in it. Although I can not visibly see any holes, obviously there has to be one. $6 later and the problem is solved. Again, thanks to all of you.

Pmart60

 
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