H card leaking

I have a farmall H I just rebuilt the carb in and it
wont stop leaking gas when I shut the tractor off.
When I rebuilt the carb the needle, seat and float
were replaced and the float does not appear to be
catching the sides of the bowl. 90% of the time
after I shut the tractor off the gas starts pouring
out like a faucet and will only stop after I tap on
the side of the bowl or shut the fuel off. Any help
would be greatly appreciated.

tapping on side of carb. bowl float is sticking tapping jars it loose.

Float rubbing the bowl some where. Tapping vibrates enough to let it shut off the gas flow.

I can not see where it is rubbing. I have pulled this thing apart at least 20 times and I see no sign of rubbing and it does not appear to be crooked. I am pulling my hair out on this one.

I can not see where it is rubbing. I have pulled this thing apart at least 20 times and I see no sign of rubbing and it does not appear to be crooked. I am pulling my hair out on this one.

The pin that holds the float might be binding.

When I take it apart the float moves up and down freely with no issues.

common problem on old gravity fed carbs, zenith carbs on case tractors really bad about it. If it runs good leave it alone and shut the fuel off at the settling bowl when shutting down.

Pin- hole in pontoon raises fuel level, omitted needle seat gasket raises fuel level, too much crud in fuel system and/or missing or damaged carb filter, incorrect float setting.

You are overlooking something simple that you just haven't seen yet. BTDT on a Zenith on an SC Case. Had it apart a zillion times and I think I have it solved (maybe). I finally rigged up a gas tank that I hung above the work table and hooked it to the carb while I was holding the carb above a pan so I could see how it performed without putting it back on the tractor. It helped a lot.


One of the bits of advice I got from the guys here on YT is to tap the new needle into the seat lightly with a screwdriver handle or something else that's light. One responder said he finally took out the new neoprene needle and put the old steel one back in and that solved the problem. After looking at the alignment of the float umpteen times, I found the tabs that the hinge pin go through on the carb weren't quite aligned right. After some tweeking with a hammer, yes, I adjusted the carb with a hammer LOL, I pretty much got the problem solved but I'm not holding my breath yet. The floats don't have much room in the float bowl and it's darned near impossible to see them after the carb is assembled. Is the tab on the float that pushes on the needle straight and not cocked? It's just an idea. Marilyn just advised me it's time to leave for church, Good luck and don't give up. Jim

I hate to say it - but I don't think there's an easy answer.

If there is, I'd sure like to hear it.

But I've been through that routine 1000 times - if you can get it to shut the fuel off properly then it's too tight and won't let enough in.

You just have to keep playing with it and eventually you'll hit the sweet spot - maybe.

The floats these days are so bad - look straight down on them and I think you'll find they're FAR from symetrical. I just had to pull mine the other day because it wasn't running right, and found on of the floats actaully FELL OFF. AND the other was full of gas! (less than a year old)

Or - you can just live with it, and resort to turning the gas off every time you shut the tractor down - which is actually something you should do anyways.

In fact - that's how I turn my tractor off. Cut the fuel and let it run dry.

Make sure the gasket is not hanging over the inside edge of the carburetor bowl. Might have to trim it.

Put a kit in my 60 tractor and the needle was too big to enter the seat without binding. Took a file and dressed the three sided needle for a looser fit and solved the problem. Joe

Did you put a new seat gasket under the needle valve seat? Also I have found many of the imported kits are just pure junk. I have not found many US many kits anymore either. Look down into the needle valve seat. I have seen the hole be off centered in some of them. Also look at how square the tangs on the carburetor are. Then check the ears on the float itself. Make sure it is pivoting freely on the pin but is not too loose. A loose fit on the pin can let it cock when the gas lifts it. Making it bind or not push on the needle square.

Something is either binding or not letting the needle valve seat. When you are banging on it you are making the needle seat. I have a little air pumpand gauge off of a blood pressure cuff. I have several hoses that will fit the different carburetors. I turn the carburetor upside down and pump up some air pressure. You would be surprised at the number of them that will not hold any pressure at all. I then spray some soapy water around the needle valve and seat. You then can see what is leaking.

I do not like the rubber tipped needle valves. They sound like a good thing but in practice I have found them to not seal repeatably at the same height. They can vary a little bit. That makes the fuel level a hit or miss thing. The solid steel needle valves will repeat much better. Also the rubber tipped one will stick small rust particles in the rubber and not seal either.

Just check what you are doing very carefully. Something is not working correctly. I have taken them apart so many time I would swear I was going to wear the screws out.

Another thing I do on all the paper gaskets in a carburetor. I have a small pan of 30 weight motor oil. I soak them in the oil and then massage it in before I install them. It soften the caskets and makes them last longer. Plus you can get the carburetor back apart with out tearing the casket down the road.

Yes all the gaskets are new and everything seems to be moving freely when I take it apart. If I turn the fuel on (when it is apart) I can lightly lift on the float and the needle will seat and shut the fuel off. I will have to pull it apart again and look it over again.

Several years ago i had a similar issue with a "B" Farmall with a Zenith. I rebuilt the carbuetor and it seemed to work well and ran good but when I shut it off it would soon seem to drip. Over the next couple years i had it apart perhaps not 20 times but perhaps 12 times still using the same gasket. With ehe bottom portion off it would stop running through the seat if I would push up on the float. One day I took it apart and discovered that he gasket had one less hole than the carburetor body had. Imade a small hole in the gasket and some 30 years later the old carburetir is still doing its job. This was the smallest hole in the gasket. I think the hole allowed for a vent to keep it from siphoning.

Absolutely correct. I have had to punch an extra hole in the bowl gasket on the last 2-3 of the kits I have put in Zenith carbs.

The needle can (and does) get slightly crooked in the seat and leaks.. Adjusting the levelness of the little tab the pushes it up will correct that. To see what is going on, take the bowl off while the carb is on the tractor, and gently hold up the float and turn on the fuel. Use a pan under it to catch fuel, but looking at it is far better than guessing. Jim

I have had those neoprene needles hang up too, so I reuse the old steel one.

Paul, I've gotta take a look at the gasket in my SC Case Zenith carb that's been giving me fits. No vent hole just might be the problem. Jim

lavallj3,
I have a small 2004 loader/backhoe that came with a 12v solenoid that shuts gas off when it's not running. You can get solenoids off ebay for around $15.

I had a briggs mower that no matter what I did, couldn't get carb from leaking. When it leaked, it filled the crankcase with gas. Installed an ebay solenoid, problem solved.

Yes the best thing is to fix it, but there are times, with $4 gas, you may still want to install a solenoid.

The solenoids on ebay come from china on a slow boat. Last time, I ordered 2, so I have a spare one sitting on shelf for the next tractor that decides to leak.
George