carburetor overhauling

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  #1  
Old 08-02-04, 10:27 AM
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carburetor overhauling

Hello everyone,
I'm working on my mower adn damaged the carburetor. It's a "walbro" brand. Where most carburetors I've tinkered with had rubber float valve seats this one is brass; the rubber is on the float valve needle. I didn't notice this until after I'd torn up the brass seat.
My question is: How do I extract the valve seat? It's a hollow brass cylinder, I can get one mail order for five dollars. If I can't get it out I'll have to buy a new carburetor or pay to get this one overhauled: either way, over a hundred dollars.
Martin Kelley
 
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  #2  
Old 08-02-04, 01:43 PM
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never mind about the valve seat, the carburetor is flooding.

I got some advice on pulling out the brass valve seat and that part is done.
I sprayed out the carb and re installed it, now it runs for maybe ten seconds and dies, blowing fuel out the air inlet. I'll try soaking it overnight. The kit I bought includes a main jet. Perhaps I ought to replace that too? If I do, is there a risk of getting it in the wrong depth? does that matter?
Help!
Martin Kelley
 
  #3  
Old 08-02-04, 02:45 PM
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Your description of the problem is good but the carb description is too vague. What are the ID numbers of the engine it's attached to. As for the blowing fuel out the inlet, I assume you mean back out the carburetor throat...This would indicate either a timing issue or more likely a valve issue. Let us know what engine you have as well as what application it's on.
 
  #4  
Old 08-03-04, 07:34 PM
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further investigation shows,,,

I've narrowed my problem down to flooding. The needle valve of the carb is not shutting off the flow of fuel into the bowl allowing it to overflow and flood the piston cylinder. I've verified this by connecting the fuel line and holding the carb in my hand and seeing the fuel flow out onto the ground. I took the bowl off and found that I can seat the needle by pushing the float up with my hand, thereby shutting of fuel flow. The float has no leaks; it floats in a can of gasoline. When held under the surface, it does not take on any fluid. I've played with the float on the chance that it was hitting the bowl keeping it from rising but didn't get any improvement in my symptoms.
Next step, new carb.
oh, well.
Martin Kelley
 
  #5  
Old 08-03-04, 10:02 PM
Azis
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First off, what machine are you working on? It makes a big difference and Walbro makes carbs for anything from 50$ trimmers to Multi mill $ baja rigs. Any kit for a float carb should come with a new needle valve and or insert or seat if equiped. Depending on what you have will depend on if which or what needs or should or could be replaced.
 
  #6  
Old 08-04-04, 05:17 PM
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pertinent data

The equipment I'm trying to fix is my snapper brand riding lawn mower.
model number: LT120g30bb

It has a Briggs and Stratton engine.
model number:283707
type number : 0134-01
date code: 9512187b

My local hardware store has a small engine shop. I got a rebuild kit, briggs p/n 697884, that had a new brass seat in it, I changed that seat, no help. changed the needle twice, no help. the seat does not appear to be leaking, as I can shut it using finger pressure on the float.
Martin Kelley
 
  #7  
Old 08-04-04, 06:57 PM
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Check the hinge part of the float and carburetor. Make sure the float is absolutely free to travel with no resistance. A rusty hinge pin can cause just enough resistance to allow leakage sometimes.
 
  #8  
Old 08-11-04, 08:27 PM
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hinge - no luck

So I checked the hinge side of the float, no visible problems. replaced the float pin - no joy. so I ate it and paid for a new carb and have had now some success; it doesn't run fuel freely now.
So I get it all put back together, new air filters and all, and find that it is still dying on me , apparently due to flooding but the flooding seems to be coming from the valve cover breather. So this must mean the valve guides leaking fuel? I think it has some oil in it too, but maybe that's ok; there should be oil on the valves, right?
Martin
 
  #9  
Old 08-12-04, 01:31 AM
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You see fuel coming out of the breather tube? From the engine end or the carb end? Valve guides won't leak fuel unless the engine is flooding terribly (as in cylinder full of liquid gas). Did you change the oil after all the flooding problems? If not, the oil is probably thinned down with fuel, and is leaking and blowing out past the valves, rings, etc... and needs to be changed. The engine should not be run like this.
 
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