# Gas leak after rebuilding mower carb?



## SeniorSitizen (Sep 10, 2012)

It's difficult to be a DIY'er with a toddler and a child. Before it causes a fire, take it to a shop for repair and while there determine if they have a mower to rent for the child wife to mow with while the repair is taking place. You can watch her mow while caring for the toddler.


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## joecaption (Nov 30, 2011)

Take it outside, add a small amount of gas to the tank, remove the bowl bolt and bowl, gas should be running out, lift the float, gas should shut off, if not the float may be sticking or there's trash blocking it.
While the float was off did you shake it to see if there was fuel leaking into the bowl?


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## Brainbucket (Mar 30, 2015)

That bolt you didn't crank down on was a banjo bolt. It should have a copper washer on both side of the line. It needs to be tight but you were smart not to crank down as it will snap. The inside is hollow so gas can flow through. Just tighten until the leak stops. But be sure that is were the leak is first.:vs_cool:


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## lenaitch (Feb 10, 2014)

If the leak is from the bowl area and it's not a loose fastener/fitting, Joecaption's post is a good test. Does the float seem to move freely? If not, it may be that the little rod that acts the pivot is bent slightly. If you have the bowl off, can you hear liquid sloshing in it? They are thin soldered metal and could have a pinhole and if it won't float it won't close the needle valve. If your mower doesn't have one, drop into a small engine store a buy a fuel shut-off tap. They're like $3.

Don't begrudge the missus needing help with the toddler. She just spent a recent 9 months building it and has gone through physical, hormonal and mental changes we mere males can't imagine. Little ones are 24/7 mentally and physically and will likely be her singular focus for a while.


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## ChuckF. (Aug 25, 2013)

Check the fuel line from the tank to the carb too, if it's rubber it could be rotting away from alcohol in the gasoline.


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## ukrkoz (Dec 31, 2010)

Go to any parts store, buy inline gas shut off valve and two garden hose clamps. Install it into the fuel line and simply shut gas flow after use. As it's carburated, you will need to open it for flow few minutes before use, as it takes some time for gas to get into carb. That's it. I have this for 2 years on my Craftsman riding mower.


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## Oso954 (Jun 23, 2012)

It wouldn't surprise me if his mower already has a gas shut off valve. 

A lot of people don't use them even when factory installed. Many don't even know they are there.


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## crash525 (Apr 3, 2013)

Check all hoses for dry rot and cracks. You also might not have connected a fuel line correctly. Double check that. 

Next check to see if the the carb has an over flow hose, most likely not. But check to see if you have gas running out of the carb intake. If so your float is not working correctly. Its stuck open or not adjusted right. 


Sent from my Nexus 6P using Tapatalk


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## Solaritu (May 27, 2014)

Took a while to get back to this. So I picked up an inline shutoff as well as a non-fuel pump fuel inline filter and added both to the fuel line. The shut off valve helped a lot, it fixes the issue, when it is shut off as it maintains a vacuum on the fuel still in the line, like holding the top of a straw and keeping water in the straw. The inline shut off, treated the symptom, but didn't fix the problem. My only other thought was to get a new float, which the other one looked fine. It took weeks to get to me, though I installed it yesterday. When the pin seats into the valve, no fuel comes out for either float, so I determined it wasn't the pin. My next thought if the pin is working, it must the float. I replaced it and still had the problem. I am not a carb expert, but I love learning about how things work. I see the fuel is coming out of two holes on either side of the big hole where the butterfly valve is located. It is a small flow, though still a problem. From what I read it is usually the float or the pin/valve. I did a complete rebuild and cleaning of the carb, any other ideas?


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## de-nagorg (Feb 23, 2014)

Flooding:

Do you have the tang on the float adjusted so that it actually presses the needle to shut off the flow?

ED


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## Solaritu (May 27, 2014)

There are three prongs that the needle slips into, here is the float I got, which looks identical to the one I have: https://www.amazon.com/gp/product/B002WNT5SQ/ref=oh_aui_detailpage_o04_s00?ie=UTF8&psc=1

I don't know what a tang is 

Prior to the rebuild and spark plug replacement the mower was running like crap and was leaking IIRC. Now it starts on the first pull and runs great, though I just want to remedy the leak. I do not want to rely on low gas levels and shut off valve. 

Maybe I should double check the needle o-ring, forget which way I installed it, ridges pointing toward or away from needle. In any case would a wrongly installed o-ring shut off the fuel when I push the float up manually? On both floats, the tabs that hold the needle have pretty loose tolerances. I don't see any way to adjust the float or the ratio. I think this one is my carb: https://www.partstree.com/parts/bri...engine-rewind-starter/carburetor-fuel-supply/

Statistically speaking according to all the reading/research I have done, it had to be the needle or o-ring I replaced and I am guessing I might have installed it wrong. From what I am reading I can say now with confidence that the ridge in the oring should be facing the needle, I will see if I installed it correctly. AT the time I installed the o-ring ridge to the way I understood it. I really can't find another reason for the leaking, granted when people diagnose the needle and valve they hold the float up to close it. When I tested it, I didn't see anything leaking. I have to rely on others experience or more trial and error.


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## de-nagorg (Feb 23, 2014)

I've called it a tang for over 50 years, others might call it a tab, or ?/,

Anyway, it's the part of the float assembly that presses the needle into the seat to shut off the fuel flow.

While you have it apart check the needle rubber tip for a ring wore into it, this will cause it to leak and makes it faulty.


ED


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## Solaritu (May 27, 2014)

de-nagorg said:


> I've called it a tang for over 50 years, others might call it a tab, or ?/,
> 
> Anyway, it's the part of the float assembly that presses the needle into the seat to shut off the fuel flow.
> 
> ...


Tang might be the proper word for it, I called it a tab, my wife would call it a thingy. The tab looks like a 3 prong fork that is part of the plastic float with the middle prong being lower so you can slide the needle into it. It doesn't use the old paper clip style holder that I have seen on some carbs.

I replaced the needle and the ridged oring that the needle sits into when I rebuild the carb about a month ago. Everything is new, except for the housing, bowl, butterfly valves, banjo bolt, plastic rods holding butterfly valves in place. I replaced the following:

All orings/gaskets
Needle
float
float pin
spungy felt pieces that sit above carb body and has butterfly valve's shaft goes through it.

I cleaned the bodies mating surfaces with carb cleaner and a brass brush. I sprayed every hole I saw with cab cleaner. The mower is only a couple of years old.


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## de-nagorg (Feb 23, 2014)

Those floats used to be made from brass, with tangs that were bendable to adjust the tension on the needle and seat.

Now they are all plastic, and I would not be trying to bend it to adjust.

When scrubbing with a brass brush, did you happen to scratch some of the plastic mating surfaces deep enough to allow fuel to seep out.

If so you need to buy a new carburetor., or use some R T V gasket maker, in a tube at the car parts store.

ED


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## juiceman39 (Jun 19, 2017)

the newer of the old lawn boy 2 cycle (mine a 2004) have a problem with leaking gas. everyone I knew that had one, put on a shut off valve inline before carb. lawnboy replaced metal carbs with Plastic carbs. Result- gas leakage.


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## ukrkoz (Dec 31, 2010)

Yep, I did just that. Shut off valve. Works great and I am very diligent about it.


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