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Carburator help - Big Ten - desperate for ideas!


Buickgsman

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I got the Big Ten running and I am happy with how it sounds. It was a great deal for what I paid... BUT the carb insists on leaking fuel. I cleaned and rebuilt the carb with all new parts but she still leaks past the needle. I set the float level a little low to try and eliminate this with more pressure on the seat but it still insists on leaking. Another thing I am also noticing is that my new fuel cap has fuel up on top of the gauge and also I found some on the tank. Should there be fuel in the top of the cap? I cant imagine that would help it live a long life. How about the carb, any ideas? As far as I can tell the float is ok. I didnt hear any fuel in it when I shook it. Thoughts? Thanks Bob
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Bob, Is fuel clean? grit can get stuck in float needle valve. -or- I would put the float Level...If the float is at proper level and the needle valve on the float is new, then it can be the seat (the part of carb that the needle valve "seats" against) on alot of carbs the seat can be changed, but not sure if these are. Check the first two ideas 1st...Good luck sm01
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Will the old needle work? I've found about half of my new needles in the carb kits insist on flooding...I use the old one quite often and they usually work fine.
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I have the same problem right now with my big ten. I added a fuel shut off valve in the fuel line and just shut that off and let the carb run dry. I hope to tackle this issue as well come spring time.
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Have you taken out float to check for pinholes? I had one to those problems also. All you need to do is immerse the in a can/dish of gas large enough to cover it.
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The carb on my 3410 leaked after shutdown, even after numerous rebuilds. I replaced it with a NEW carb bought from the dealer. It also leaked.....XX( Put on a fuel shutoff, and never looked back.:)
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Today I switched out the float and tried it and it still leaked.. So then I switched the entire top piece of the carb and it still leaks. Not cool! I had thought about just ordering a new carb but I would flip if that didnt solve the problem. The carb I have looks good so I cant figure out the problem. So, just to recap, these carbs should NOT leak gas into the lower air/ choke area correct? Also, another question.. should the fuel gauge have gas up in it visible on the fuel indicator and clear plastic lense? How about pressure in the tank, should there be any? Or, should I ask if the cap should be vented? Thanks Bob
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Still leaking.. this has me puzzled. Is there anything that could be going on with the motor that could cause the carb to leak? This shouldnt be this difficult.
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There are two places that these carbs leak. One is the float needle. Make sure that it has the neoprene tip on it. I bought a kit that had a solid metal tip. That will not seal in the older carbs. Some of the newer carbs have the solid needle with a rubber seat. The old ones have a metal seat and a needle with a neoprene tip. You cannot get the metal needle to seal against the metal seat. The second leak point is the conical seat on the emulsion tube. If the emulsion tube is not tightened properly, if the seat on the tube is damaged, or if the seat inside the carb is damaged, it will leak gas into the carb. No amount of messing with the float will cure this leak. In the picture below the green line shows a leak from a float that does not shut off. The blue line shows a leak from an emulsion tube that is not seated.


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What Hubbard just stated can be taken as gospel. 100% correct...Sorry Bob I didnt mention the solid metal float needles are terrible, use only neo-tipped, Did you change the high speed tube? as he said it needs to seat/seal to carb body
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How would I be able to check if the emulsion tube is seated properly? I bet this is my problem because the fuel has to be coming from somewhere other than the float. I tested the float and needle the best I could. I removed the carb top and turned it upside down and turned the gas on and nothing came out the needle so it is sealing with the weight of the float so i would assume that the float would keep the needle shut. The pic above is exactly what I was looking for. I will see if I can figure out if the tube is seated properly. It's tight in the fitting i know that. Any good way to test this out? Thanks! Bob
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Oh, and yes I am using a float with the rubber tip and the metal seat. I have one carb that the seat is replaceable and another that is just aluminum and not replaceable. Bob
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Think I read somewhere on here that someone put a small o-ring on the nozzel and pushed it back to the threads. I believe it was Roy. I have two carbs doing the same thing now. Both I rebuilt with new viton tipped float needles and they are still leaking into the carb body. Think I am going to try a small o-ring on the nozzel.
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Here is the link it is a teflon wasker. I will do some more digging. http://www.simpletractors.com/club2/topic.asp?ARCHIVE=true&TOPIC_ID=14856 http://www.simpletractors.com/club2/topic.asp?ARCHIVE=true&TOPIC_ID=2146&SearchTerms=leak http://www.simpletractors.com/club2/topic.asp?ARCHIVE=true&TOPIC_ID=2425&SearchTerms=leak
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I tried the teflon washer on one of mine but could never get it to seal. They kept bunching up and tearing. Don't remember how I fixed that carb. I think I replaced the emulsion tube and that worked.
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I think the emulsion tube is your problem, small o-rings can be had at any hardware store, whiite litium will help keep it from tearing the o ring, but there has to be air pushing fuel back thru the tank to have fuel get into the cap (unless you had tank really full and bounced the tractor around before getting it into the shop) Did the carb backfire? That might explain the back pressure enough to get fuel thru the cap. The B&S filter and fuel shutoffs work well and are installed in line, an easy way to make sure no fuel leaks onto the garage floor!
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My diesel will get fuel in the cap and that vibrates like mad. If it is filled to the top it will do that as well. I think I used an o-ring on the nozzle of one of mine but it was along time ago.
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I tried just about everything I could today to get it to stop leaking. I cleaned the mating surface in the carb for the emulsion tube sealing surface, I even used a small amount of RTV on the emulsion tube threads to try and stop the leaking but it continues. I get a bit anal with this kind of stuff so I will do more research to try and make it right. My worry isnt so much with this Big Ten I picked up, but moreso the Landlord when I get that running. I dont want a leaky carb to make a mess of things. I also am not a fan of having to shut the gas off when I am done with it although it may come to that. Any other ideas or suggestions are appreciated. Thanks Bob
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Most of ours leak and I gave up on fixing them! As i have had new parts installed in them and apart to many times! We just turn in line shut off valve off each time and let it run until out of fuel.
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Bob, Have you checked the mating surface of the bowl? They can get warped especially around the screw holes. That can be corrected by laying a sheet of fine sand paper on a hard surface and gently working the bowl in a circular pattern. A piece of glass works well for a flat surface.
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Bob, way back inthe begining you said you set the float a bit lower. I said you should set it to proper level...Did you? No way all this trouble with out either a bad part or bad adjustment. I would go back and redo each step "by the book" no add-ons or mods.(I always say dont try to out engineer the engineers) But OEM Briggs carb parts may help too, I know some I got are china specials...Good Luck ps, gas in the gauge is normal if you top the tank. but it needs to breath, its a vented cap
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