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HubbardRA

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HubbardRA
I have been having carb problems on a 12 Hp B/S large body updraft. I thought the float needle valve was leaking because the engine will run beautifully for about 30 seconds then gas will start to drip out of the carb and the engine will run rough from too rich a mixture. I have noticed that when I remove the carb, the fuel bowl is completely empty. A leaking needle valve won't empty the gas from the carb. I think the leak is at the seat of the emulsion tube where it goes through the float reservoir. I changed that tube when I put in a rebuild kit. It didn't do this before re-build. Unfortunately, I can't find the old tube that I had removed. Has anyone else had this problem with one of these carbs? Does anyone have a solution to fixing this type of leak?

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PatRarick
Are you sure you used the correct carb kit? There are two kits, depending on the age of the carb. One is 391071, and the other is 394693(or 698, can't readily recall). I have looked for the difference between the 391 and 394 kits, and the only difference readily noticeable is that the nozzle is a little longer on one than the other. It may be that the taper of the sealing area is also different, but I can't attest to that. To my knowledge, the correct kit is determined by the date code of the engine, so if a newer carb is installed on an older engine (or vice versa), it would be pretty easy to get the wrong kit. There is a possibility that the sealing surface for the nozzle is damaged by corrosion, and the corrosion sealed the old nozzle. Also see this post, in which I replied as to repairing a leaking nozzle: http://www.simpletractors.com/club2/topic.asp?ARCHIVE=true&TOPIC_ID=14856&SearchTerms=leaking,carb Pat

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HubbardRA
Thanks Pat! This is what I needed to know. There were differences in the tube. Now I need to find what I did with the original tube. Carb didn't need a re-build when I did it. Had a vacuum leak between carb and tube. Should have followed the old adage "If it ain't broke, then don't fix it". I had purchased the parts so I put them in. Fixed one problem and caused another.

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patrician12
10,12 and 16 2 piece flojet to my knowledge and past experience use the same carb kit.Where the tube goes thru the float chamber are notorious for leaking past the tapered seat.Sometimes stoppable and sometimes not.I like to put a sealer on the threads and let it sit over night.The gas leaks past the tube into the intake area and causes a drip.On one occasion only did I have to go for a new carb.

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Al
Hi, There are some little plastic washers, a shim kit for the 5 hp tank mounted carbs that work well for to put over the seating area for a seal. I will have to get the Briggs part number, I believe there are 6 or 8 in the kit. Will post pn later. Al Eden

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Bunky
Is there anyway to tell a early carb from a later model one???? I think that I may have this same problem with the nozzle on my 7010 and 3410S and one has the choke lever ( Where you hook the choke cable) on the outside and the other has the choke lever on the inside toward the shroud...

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PatRarick
quote:
Originally posted by Al
Hi, There are some little plastic washers, a shim kit for the 5 hp tank mounted carbs that work well for to put over the seating area for a seal. I will have to get the Briggs part number, I believe there are 6 or 8 in the kit. Will post pn later. Al Eden
Al, the part number for the washers is 391413. It's posted in the link on my reply, above. They do work well for this repair, most of the time. I have quite a supply of the little roll pins!! Pat

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HubbardRA
I noticed today that there is a small undercut on the tube with a tiny hole into the tube. This was not on the original tube. Is this for the newer carb? Could that hole be the leak, since it is behind the seat?

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