Zenith carburetor

[Mtjohnso]

Have a Zenith Carburetor (12566) updraft that apparently was used on a lot of different engines. This one is on a John Deere 1010 crawler. Fuel is gravity feed to carburetor.
Initially the carburetor would leak gas out the bottom of the carb when the engine was off. So you always had to turn the gas off at the tank when engine was off.
So I bought a carb kit from a local shop only to find that the carb kit was wrong. Carb shop owner found parts to replace needle valve and seat and correct gaskets.
Put it all back together and back on the engine and turned the fuel on. Carb immediately had fuel coming out of it. I assume the needle valve was not closing.
Pulled it off the engine. Needle valve was not stuck. Blowing into the inlet with my breath and the needle did close it off.
Thoughts on why this maybe happening.

 

[Bruce(OR)]

Debris on the needle holding it slightly open or the good old fashioned wrong float level.

 

[r.w.b.]

or pinhole in float

 

[caterpillar guy]

Float dragging on the side of the bowl, set wrong,hole in float,different gasket thickness, needle and seat not sealing well, pin slid out of position. several things here.

 

[Geo-TH,In]

I had the same problem with my zenith carb on my 1950 Farmall C.

I ordered an aftermarket carb off amazon.

Dosens Carburetor Compatible with IH-Farmall Tractor A AV B BN C Super A Super C Replace 352376R92 TSX156 TSX157 TSX319 354184R93 355485R91 373957R91354184R93 373957R91 52499DB 69401D
$33.69
It took me a while to get it adjusted correctly.
What do you have to lose if you ordered one from Amazon?

I figured if it didn't work I could send it back to Amazon.

I also ordered a rebuild kit from Amazon.
The gasket was damaged and the needle valve was the wrong one.

 

[UncleTom]

I always use a Q-tip in a drill and clean the seat with carb cleaner weather it is new or used. I also have a low pressure pump and gauge i made from a blood pressure machine. I pump the inlet down while holding the float up to see if it holds 3 pounds of pressure. Why not find out if it holds before you get the carb back together and on and only to find it doesnt work. I dont have to guess anymore what is wrong. I mainly use it on Walbro and Zama carbs on chainsaws and leaf blowers. It will also find a bad fuel line.

 

[Gary Mitchell]

In my experience, and I've rebuilt a few carbs, about half the ones I did, when I put them back on and turned on the gas, I had to whack on the side a couple of times with my Wilde pliers. Try that before you spend another nickel or pull out more hair. gm

 

[ken44520978]

Years ago I fought and fought a carburator on a single cylinder Wisconsin motor doing the same thing. As soon as I turned the gas on it would run out where the air filter connected. I finally found a plugged vent that vents the air out of the bowl as the bowl fills. If the bowl cannot vent the air out as gas runs in, gas will be forced up a port somewhere and run out of the carb. You may need to use a small diameter wire and poke around every hole you find to make sure nothing is plugged.