Guess what happened again.

Needle valve is sticking again in my A's Zenith carb. Lasted close to 2 years this time, mainly because I drain my gas tank after every run and refill it before the next run. Zenith needle valves are hard to buy too, most online vendors do not sell them, but Marvel parts are all over the place.

Read on one site where a guy after cleaning the new seat and needle, sprays silicone lube on the needle tip then lets it dry before installing. Think I should give that a try?
 
If you let it sit between use for more than a year, it makes some sense to drain the tank. If not, you should be shutting off the fuel at the tank and running it till it stops. this opens the needle valve, and when the tank valve is opened to use the tractor, the inrushing fuel will sweep the seat clean. Always shut off the fuel at the tank, but if the use is weekly, just leave it as is without running to stop. Jim
 
(quoted from post at 14:10:06 03/26/17) If you let it sit between use for more than a year, it makes some sense to drain the tank. If not, you should be shutting off the fuel at the tank and running it till it stops. this opens the needle valve, and when the tank valve is opened to use the tractor, the inrushing fuel will sweep the seat clean. Always shut off the fuel at the tank, but if the use is weekly, just leave it as is without running to stop. Jim

I always shut the fuel off when I shut the engine off. Then I disconnect the fuel line and put in a sealed gas can as the open vented gas tank allows fuel to go bad pretty fast. I will try running till empty next time.

The Zenith carb is pretty new, just the needle valves end up sticking after some time, rest of the carb is fine. It is not economical to buy a rebuild kit just for a needle valve. There are a few sites that sell them individually. Shame this site doesn't. For the Marvel carbs they list the needle valves being Viton but they do not state if Zenith needle valves are Viton, so I suspect they are not. Guess they think there is not enough of a market for Viton tip Zenith needle valves.
 

Forgot to say that knocking with a screwdriver, or even a mallet doesn't seem to work. Once it starts sticking, its done. I will test the silicone spray and see how well it works.
 
Have you tried putting Stabil in your gas? I have been using the new Stabil 360 that cleans, stabilizes, and fogs the tank. I shut the fuel off and let it run for a bit, sometimes waiting for it to start to miss sometimes not. I had my tiller, mower, pressure washer, zero turn mower, generator, and one of my tractors sitting for 4 to 6 months and they fire off immediately. No sticking needle valves and no bad gas. Some were full tanks and some had partial.
 
(quoted from post at 12:26:11 03/26/17) Needle valve is sticking again in my A's Zenith carb. Lasted close to 2 years this time, mainly because I drain my gas tank after every run and refill it before the next run. Zenith needle valves are hard to buy too, most online vendors do not sell them, but Marvel parts are all over the place.

Read on one site where a guy after cleaning the new seat and needle, sprays silicone lube on the needle tip then lets it dry before installing. Think I should give that a try?

Brand new needle valves have some kind of protective film that cause them to stick. Clean them with aerosol carb cleaner, allow to dry, and then spray some silicon lube on it. USED needle valves should NOT have that problem.

You say you drain the fuel tank after every run, but are you draining the carb also? I will suggest that after every run, you shut the fuel off at the sediment bowl while the tractor is still running and wait for the engine to die. THEN go ahead and drain the tank.
 
I don't think I'd spray any of that carb cleaner on a needle that has a rubber or neoprene tip. I think it would eat it. gm
 
(quoted from post at 11:52:56 03/27/17) I don't think I'd spray any of that carb cleaner on a needle that has a rubber or neoprene tip. I think it would eat it. gm

NO, it will not eat them up. If the carb cleaner would effect them, so would gasoline, and for what it's worth, ethanol has no effect on them either.
 
(quoted from post at 08:55:38 03/27/17) Draining the fuel tank is a waste of time and effort. The fuel in the tank can't do anything to the carburetor.

What I noticed is when the gas in the tank phase separates over a winter, the Ethanol leaks past the fuel shutoff valve and into the carb. I can see this through the glass fuel strainer. This is pure Ethanol leaking past and probably very harsh on the needle valve. Even if it didn't leak past the shut off valve, as soon as it is opened the separated pure Ethanol would hit the needle first, wiping it out pretty quickly. Regular gas does not appear to leak by the valve.

Other issue is the gas tanks are open vented, which exposes gas to outside moisture which speeds up phase separation. A good gas can is sealed and keeps moisture out, hence why E10 stays good longer in a sealed can than in a open vented tank. Makes me wish Farmalls had Evap systems like cars do for closed venting and keepng moisture out. Other issue is most cars and trucks are top feeding fuel tanks, not old bottom, gravity feed fuel tanks where motors ingest pure Ethanol first if phase separation has taken place. Modern fuels and oils are designed for modern stuff only with no regard for old stuff. :(
 
(quoted from post at 14:36:09 03/27/17)
(quoted from post at 08:55:38 03/27/17) Draining the fuel tank is a waste of time and effort. The fuel in the tank can't do anything to the carburetor.

What I noticed is when the gas in the tank phase separates over a winter, the Ethanol leaks past the fuel shutoff valve and into the carb. I can see this through the glass fuel strainer. This is pure Ethanol leaking past and probably very harsh on the needle valve. Even if it didn't leak past the shut off valve, as soon as it is opened the separated pure Ethanol would hit the needle first, wiping it out pretty quickly. Regular gas does not appear to leak by the valve.

Other issue is the gas tanks are open vented, which exposes gas to outside moisture which speeds up phase separation. A good gas can is sealed and keeps moisture out, hence why E10 stays good longer in a sealed can than in a open vented tank. Makes me wish Farmalls had Evap systems like cars do for closed venting and keepng moisture out. Other issue is most cars and trucks are top feeding fuel tanks, not old bottom, gravity feed fuel tanks where motors ingest pure Ethanol first if phase separation has taken place. Modern fuels and oils are designed for modern stuff only with no regard for old stuff. :(

ALL fuel tanks draw from the bottom. It may not look that way because the hose comes out of the top of the tank, but that hose goes all the way to the bottom. For what it's worth, I have an H with E10 in the tank. It has not had any fresh fuel added for a full 2 years. I just don't use it very much. I am
confident I could start it up today and it would run just fine. I have never experienced any kind of ethanol seperation.
 
most cars and trucks are top feeding fuel tanks, not old bottom...............
Are you kidding us!?! How could you use the volume of the tank? chuck.
 

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