Stuck needle valve?

How do I fix a stuck needle valve on my MS carb on my TO35?

Gas is running in the tube to the carb but the carb will not let any in, i.e., when I open the brass plug on the carb's bottom no gas runs out. The screen at the carb is clean.

When it sits on my bench I can not blow air (from my mouth) through the gas inlet unless I manually open the needle valve with my finger nail.

I thought that a cranking engine would open the valve.

How can I get the valve to slide more smoothly?

Thanks for your help.


George

Without taking it apart...Smack the side of the carb with a screwdriver. This might help to free a sticky float. If not, rebuild is in order...

I am having a problem with my TO 20. Sediment bowl is clean. Screen at carb is clean. Pull plug from bottom of carb and the gas flows freely. It will run decent for 10 minutes or so, then you have to go to full choke to keep it running. Whack to the side of carb makes no difference. Is it ready for a carb rebuild?

8f14, there is a screen in the fuel tank in the part that screws into the tank take this out and make sure it is free of debris. Also you said you pulled plug from bottom of carb and it flowed freely. How long did you let it flow? You should have at least a quart container to catch it in and let it flow, if it does not flow all the time quickly the hidden screen I mentioned is probably plugged. I say a quart, more would give you a better test. Richard

(quoted from post at 22:22:27 07/31/08) Without taking it apart...Smack the side of the carb with a screwdriver. This might help to free a sticky float. If not, rebuild is in order...

Click to expand...

Thanks for the reply. The carb is pretty new. It is only two years old with under 100 hours.


George

I"d replace the needle and seat. Might as well do a full carb kit rebuild. When you do, make sure the main jet, the one with multiple small holes that requires a slim deep well 3/8 socket to remove, is clean.

You know, this might not be a carb problem...! It could be an electrical component is heating up (in 10 minutes) and acting up as a result. Usually if the coil does this, the tractor shuts off completely. Ditto the key switch. But it could be the condensor? Have you checked for a good blue spark when it is running this way? If you have not done so, I'd do that before I tore into the carb.

George, my response to 38FL4 was just for his message, doesn't apply to you. Just fyi. I do have a response to you below.

I hear two problems; a stuck needle valve and no fuel flow to the fuel bowl.
I presume by "needle valve" you mean the main jet screw. Is that correct?
Regarding the lack of fuel, if no fuel runs out of the fuel bowl when you open the plug at the bottom of the carb, the float valve is stuck,or, the float is hung up and not letting the float valve open,or, there is so much crud in the bottom of the fuel bowl that the float cannot drop, or, the internal passage to the float valve is clogged.

Age does not matter as a matter of fact the less a tractor is used the more likely it is to have a carb problem because of condensation and water in the carb causes rust and rust them causes problems
Hobby farm

Sorry, I guess the correct name is the float valve. It's an octagonal chromed 1" piece with a ribber tip. It is controlled by the float. It looks super clean as does the float and bowl. Since fuel runs over the float valve I don't see how I can lube it.

Could the thin brass of my float have broken during all the times I've had the carb apart? Does the float wrap around the valve and yank the valve down or does the valve just drop when the float moves?

Sorry to keep asking all these questions.


George

Had a similar problem with my 35 and is was the tubes in the sediment bulb full of CRAP>
They would allow just enough gas in to get her running, but not enough to run under throttle.
Responding to some of the other posts, I actually had some floats with cracks and they would just fill up and drop to bottom of carb--letting the float needle just stay wide open..this made for TOO much fuel and the tractor would flood out and drip gas like crazy.
I make it a practice every summer to take my carb off, sediment bulb, drain gas tank, and clean air filter. My tractors sit ALL winter and its amazing the crap that's in there from year to year. A dirty gas tank can be a lifelong pain the GAS if ya know what I mean.
Mark

A cracked float sinks. Lets the float needle valve stay open. Floods the engine. You don't have that.

I can't say where the float drags the needle down or just lets the needle fall from gravity. Carburetors have been made both ways. If the float drags the needle down, there is often a groove at the bottom end of the needle that needs to be in a slot on the float arm or hooked to the float with a fancy bent wire. If the float needle is supposed to be in a slot on the float arm but is on top, the float probably can't fall far enough for the needle to open.

Some vintages of viton tipped float needles have had a propensity to stick to the seat. More than one owner has cussed them and searched for an all brass needle that might not seal as well but opens more reliably.

When I'm working on a float and needle and seat, I chcck that with me blowing air (lung pressure only) into the inlet fitting that with the bottom off the carburetor and the top upright that I can gently raise the float and it stops the air, and when I lower the float, that air easily resumes. There is also a setting for each carburetor and engine application for where the top of the float should be with the needle closed to set the gas level in the bowl. That sets the mixture during the transistion from idle circuit to power circuit and minor tweaks can sometimes affect that transition region.

Gerald J.

I cleaned the float and seat and still no gas. I just ordered the rebuilt kit so I'll let you guys know in a week or so.



George

The valve just drops when the float moves. The float could have a hole in it. Hold it in your hand and rattle it and if there is fuel inside you should be able to hear it.

So the fuel line or inlet filter is plugged. If it were mine, I'd have that carburetor top off the tractor and on the bench and I'd clean until I could blow and shut off air that I blew through with my mouth on the inlet fitting. It it won't pass air at 0.5 psi, it won't pass gravity driven fuel.

There is often a screen on that inlet fitting (not part of a normal rebuild kit) that gets plugged. Lines get plugged with varnissh, also sediment bowls and tank screens get plugged. Have you eliminated ALL of them, tank (and venting cap is important), to float needle? Any one or a combination can stop fuel flow, as solidly as turning off the valve at the sediment bowl.

Gerald J.

Thanks for all your help guys, I'm back in action!

After taking everything apart and looking at its condition I decided to put on a new carb. I used a Zenith which is about 40% cheaper than our MS carb.

I'm going to start a new thread to discuss this.