How to Fix Fuel Leaks in Lawn Mower and Small Engine Carburetors, Fuel Tanks, and More!


(Intro Music ♪ ♫) Hi, my name’s Adam and I’m going to be covering gas leaks. Now when you see gas leaking out of your mower it can be easy
just a call the repairman and think that all is lost; but there are simple ways to
identify the problem and possibly repair yourself and save some money. The first thing you need to do is wipe
it off and watch for the drip. If you can wipe it off to a condition where you
don’t see any more gas. Then you want to check to see where it’s coming from. There are five spots that I can
identify where gas usually leaks out of. These would be; First the tank. The tank along side of the seam-
sometimes it’ll get cracked or warped heat will warp it causing the seam to
separate so that gas will leak out. Also you want to check around the cap.
Caps go bad. Wipe it off, see if it’s leaking around
the bottom side of the cap. Second thing you want to check out is the fuel line.
Has the fuel line been corroded? Fuel lines go bad pretty quickly; and the rubber will
allow fuel to just drip out. Sometimes at the connection on either side of the
line will go bad. Fuel lines are cheap, they cost five, ten dollars. You can get
my Home Depot or order a real online. So change that out- if you see fuel leaking
from it. Third place that is most common: These are going to be from the
carburetor. I have three left. The bottom bolt- the gasket that surrounds it. I’ll show you what that looks like. I have a
Tecumseh carburetor here and I have one from a briggs & stratton model. I’m gonna
pull the bolt off the Tecumseh. This is just a 1/2 inch socket. You
can see right here- This would be the gasket that would hold fuel from coming
out of the bottom of this bowl. Without this gasket the bolt wouldn’t be able to
hold back much. So you have to have that in place. Put that on the side. Third thing-
Sorry the fourth in line is a rubber bowl- the rubber seal that surrounds the
top of part of the bowl. So I’m gonna pull the bowl off. If you can see
here this rubber piece seals the bowl up against the carburetor. Without that fuel
will leak all around this. and if you see- What you want to do is wipe that off and see if it’s dripping from the top side here. Same goes with the the bolt. If you wipe
it off and you see fuel coming from the bottom here dripping- sometimes you can
easily go in and just tighten that real quick. Otherwise you may have forgotten to put
the gasket back on the bolt before you put it all back together. On other times
this gasket, this one happens to be made of brass- can go bad. Others are made of just paper or
cardboard type material. In that case you can cut out your own or just buy one.
Fifth in line here is your needle and seat. I’m going to open up and show both
of these- the Tecumseh and the Briggs & Stratton model needle and seat. I’m going to need my needle nose pliers here. Just gonna pull the pin. Then pull this back. There’s my needle
that just fell out there. You can see that. Inside here where that needle
will sit it that rubber seat. These will go bad and foul out and they’ll
become hard and they need to be rubberized so that when this needle sits
against it, it stops the flow of fuel coming in. Works a lot like a toilet does
in a way that it stops water from continuing to fill the tank- until the
next flush. So yes, the there’s a kit that’s made by Briggs & Stratton I’m
sure that there’s a similar one made by Tecumseh where you can order. It’s
usually the needle and seat that you’ll buy together a kit. You’ll use a tool
that- I have one that’s made from Tecumseh. My wife said it looked just
like her sewing needle. You’ll use this to extract that rubber piece right
out of here with this hook, and then you’ll be able to put the other rubber
seat right here on the other side of the tool and shove down inside, and twist it
so you get a flat surface there. I’ll show you it’s the same way inside
the the Briggs & Stratton carburetor. Same 1/2 inch socket here. See here I have this- the same rubber
seal. So I’ll go ahead and pull the pin out. Flip this over. There you have your red
rubber seal inside there. It’s called the needle and seat. So if
you- The way to identify this last problem: If the fuel is leaking from the inside here- usually from right here, or here, or straight from the jet right
there in the center. Then that’s how you would know that the fuel is continuing
to seep up through here where the jet is supposed to be stopping it. So just remember: Wipe it off, and watch
for the drip; and you’ll be able to identify the problem and fix it.

51 thoughts on “How to Fix Fuel Leaks in Lawn Mower and Small Engine Carburetors, Fuel Tanks, and More!

  1. Most likely you need to replace the needle and seat of the carb. Either that or your float has a hole and is now full of fuel.

  2. Thanks for a detailed video. My float was full of fuel. Didnt even know anything about lawn mower engines before this video. Shop wanted $80 plus parts.

  3. Also wanted to know the name of that tool to pull out the rubber stop that meets w the needle? Where can it be purchased?

  4. Thanks for the info! On a Tecumseh 3 HP vertical shaft ice auger, With a diaphragm carburetor. When I lay it down for a while and then pick it back up vertically it leaks fuel out of the exhaust . What would cause this?

  5. Awesome video, if after all of that the Carb still leaks, than its the float. Replace the float and make sure the open end of the needle clip is put in right. Open pointy end facing the choke .

  6. gas is leaking from the air hole on the prime button. It is just sitting there leaking without me touching it. I have lost a whole tank of gas in less than a day. What causes this?
     I thought there was a tear or crack in the button so I replaced it yesterday. No difference….still leaking.

  7. Thanks for the video, helped me narrow down my problem and show the ease of fixing it.

  8. is there any reason after putting the carburetor back on that gas would leak out of the green gasket that is between the carburetor and the plastic piece that connects to the engine. when priming there is no resistance. all I hear is air unit gas comes out. The green gasket has been replace but still its leaking. the carburetor has a channel or canal that I believe the gas is coming out of. I believe its for venting.. Let me know what you think. thank you. 

  9. don't forget a saturated float ( pinholes )metal float will leave the fuel system wide open to overflow, will flow out the choke. I find this the most common.

  10. you need to make sure the spring holding the needle is pointed towards your choke side of carb. sounds crazy but it works

  11. Hi Adam.  Just watched your "solving carb gas leaks" video.  I found it informative and easy to understand…After cleaning my Tecumseh carb (it has an adjustable main fuel jet, bowl bottom drain, adjustable idle mixture and idle speed screw), I installed a new valve seat and float valve needle.  When remounted to my 1967 7hp YardMan Snow Bird Snow Thrower, gas still leaks out of the choke opening. No float level adjustments were deemed necessary during dis-assembly as the float held a slightly-above horizontal position when the carb was held in hand up-side-down.  I had a similar gas leak problem once before with a 1986 5hp Tecumseh engine whose primer bulb had lost it vent to atmosphere – boy, that was an elusive problem to solve! – but this engine has a rather rudimentary primer, which consists of a small plate attached to the end of a spring-loaded plunger, which when pushed in, simply closes loosely against the carb throat.  I carefully inspected the float to be sure that the exterior was without varnish build-up, that there was no fuel in it, and the float needle spring clip's open end is facing the choke side of the carb. I also checked to be sure that the gas tank is vented to atmosphere as well.  Do you have any suggestions?  Thank you.  PA

  12. Thanks for this video I was so close to throwing out the lawn mower that came with our new house because of a gas leak and thanks to your video I found out it was from needle and seat and I was able to fix it thanks again

  13. I've been working on my 16 year old Briggs & S a good 10 to 12 hours or so, my first time! Did everything perfect! (I thought) Learned all I know threw YouTube on this project. Rebuilt the carb, paint and all! Was all done. Thing looked bran new! Put gas in the tank, and it leaked like Feak'n Crazy! I was totally gonna trash my 10 hours of work and over 120 bucks I had put into this project and chuck it in the street for the next guy to deal with. I couldn't understand why it was leaking for the life of me! Then Came your Video. Thanks Adam. I didn't seat the toilet bowl needle thing-a-ma-bob! It's now Dry as the Valley I live in! Now to repaint this peeled gas saturated thing… Oh Well, Thanks again.

  14. Thank you fire this. It saved me a lot of time and trouble. I gained a free lawnmower too.

  15. My carb on my Honda hrr216 was leaking gas so I replaced it with a new one with . I put the new one on and it still is running gas down carburator. Can't find the leak still. Any thoughts? Thanks bud

  16. #5 was the culprit for me. Showing and explaining the tools was a huge help. I was able to use one of my wife's smaller knitting needles to remove the pin seat and a thin rod with some electric tape wound around it just off the tip (sort of replicating what you had there) to properly position the replacement pin seat. Thanks!

  17. Thanks for the video, just what i needed! I pulled the B&S carburetor off and opened it up, the float had dried on material, cleaned it up and the mower runs like a charm!

  18. Oh needle and seat I think thats why gas is spraying out air filter

  19. Thank you for sharing your knowledge with those of us who are mechanically challenged. I found your video thorough, informative, and easy to understand.

  20. my lawn mower start but leak gas at the gas line..i change it n now it start to leak at the primer..do you know why..

  21. mine was leaking gas all over the place , took gas out of tank ,took apart to get a look at the carb, poured gas in and not leaking , put everything back together and running fine. started it up once every hour for 5 hours and no leaks. question , why did it only leak that one time and what would be the most common thing for this to happen, would like your opinion adam. by the way, great video MAN!!!

  22. I just found my Sears YT3000 riding mower on my driveway covered with gas(the deck, etc.) It doesn't appear to be leaking around the fuel filter or from the fuel line. The concrete pavement under and around the mower was flooded with gas, as well(not just a little drip!) I had put gas in it a few days ago, but did not crank it. I'm assuming that since nearly ALL of the fuel has leaked out of the plastic tank, it must be a crack or leak in the tank somewhere(or maybe a bolt underneath the tank that connects it somehow?)
    Are these plastic gas tanks expensive/difficult to replace? Can they be repaired? Any other ideas? I live in a VERY hot, humid southern state…and the mower sits out in the sun.
    Thanks so much for your videos. They are very helpful for a single woman with minimal skills to follow!

  23. In the last example (needle seat), the gas on the B&S will be running out of the center hole on the prime bulb. B&S Needle & Seat is #398188.

  24. If the needle and seat are good and fuel is coming out of the carburetor it could also be fuel in the float.

  25. ethanol eats viton, the rubber on the needle is viton dont use ethanol or e10

  26. Thanks for the video. I have a problem with gas leaking thru the primer bulb without the engine running. Any ideas why? TY in advance.

  27. This fella is very knowledgeable. And very informative. Thank you. for the video.

  28. I had a leak straight out the carb into the air filter, I found out today that the gas and air vent were hooked to the other guys port. Now that is a easy mistake for an amateur to make, I have no idea how it got swapped around. But plan on changing the gas line anyway, will set it up correctly and see if that stops gas flowing out as soon as I pull the starter cord.

  29. What is the proper name for tool used to remove seat?
    I need to get that before I move forward so will await info. I brought a Craftsman mower today. 6.75 Briggs gold Ed. Guy said leaks gas $20 and can have. Mower is in clean nice shape. I can confirm leaks. Put gas in tank and gushes out air breather soaking filter. I assume untill I open carb I need to look into neddle and seat issue?

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