What is the Reason Behind Shutting Off the Fuel?

SnowStorm34 · Aug 25, 2016

Hi

I'm a tractor/mechanical newbie, but I have a homebuilt tractor that my Grandfather built around 40 years ago. While I've had this tractor for some time, I've only recently took interest in how it works/maintaining it/etc.

One question I have is related to turning the fuel off. I always shut the fuel off after running my tractor. People wiser than myself said it was a good idea. But lately I've been wondering why. I don't mean to challenge this advice, I'm just interested in understanding the reasoning behind it.

If anyone has the time to explain the reasoning, it would be much appreciated.

Anyway, a couple weeks back I gave the tractor a fresh coat of paint. Here's a pic if anyone is interested.

RM-MN · Aug 25, 2016

There is a valve in the carburetor already...but it is operated by a float that may not float at times or it may get a tiny speck of dirt in it and leak. Turning off the fuel valve will keep it from draining the tank onto the ground or into the oil sump.

ohiojim · Aug 25, 2016

second the previous answer, most old carbs will leak and if your lucky it will go onto the ground, some will fill the oil pan

W_B · Aug 25, 2016

Nice looking little tractor!

Two reasons that I know of to shut the gas off, at least on an N, (others might have more reasons) 1) if you have a leaking fitting in the line or at the carb (guilty here!) and 2) you might have a stuck open valve or a float with a hole in that doesn't shut it off (when the bowl is full, as it should) in the carb that will cause the bowl to fill up and possibly flood into the cylinders through the intake. I just get in the habit of doing it during shut down.

old · Aug 25, 2016

There are a number of reason to shut off the gas.
#1 if the float sticks which is common the gas can/will flow till it fills the carb and then over flows into the oil pan and that can mean a blown engine
#2 again carb fills but gas ends up on the ground which is like throwing away $$ plus can cause a fire.
And there is probably a few other reasons like on my 1935 JD-B that is how you shut it down

Karl in MD · Aug 25, 2016

Also, if you don't use the machine often, turning off the gas and letting it run out, then shutting off the switch, makes sure that you get fresh fuel in the carburetor when you start it again. This is often more important when you are crank starting, but it can't hurt.

dr sportster · Aug 25, 2016

One word --FIRE . Once the fuel leaks it won't take much to light it off.

BarnyardEngineering · Aug 25, 2016

Shutting off the fuel also limits how long the tractor can run if it were accidentally started. There have been cases where lightning strikes have caused gasoline powered tractors to start and drive off on their own, not to mention curious children.

If they can only run 15-20 seconds, the damage is limited. Best case scenario is when you run the carburetor dry too.

Sean Feeney · Aug 25, 2016

More about the tractor please what powers it, transmission etc... looks like he did a fine job building it

MarkB_MI · Aug 25, 2016

Gravity feed fuel system means gas can flow even if the engine is not running. If you choose to leave it turned on, chances are you'll come back someday to an empty fuel tank and a big dead spot in the grass under the tractor.

BobReeves · Aug 25, 2016

Yes, more about the tractor.. That is fantastic.

Married2Allis · Aug 25, 2016

Overheating and catching fire is a big reason. From the looks of the picture, you'll want to keep that from happening.

I restored a Cub Cadet 782 awhile back and was so anxious to get it reassembled and running I paid no attention to the carb. Took it out for a spin and decided to see how it mowed. In 30 minutes it overheated and oil mixed with fuel was 'boiling' out of the oil fill tube. I had neglected to put a fuel shutoff valve on it. The float had stuck and the crankcase filled with gas. Darn lucky it did not burst into flames.

Geo-TH,In · Aug 25, 2016

Reason I have solenoids on my tractors is
one day I opened garbage and a tank of fuel
was in the floor.

Had an old briggs, when carb leaked the gas
ended up in crank case.

37chief · Aug 25, 2016

I always shut off my gas tractors. Even though they are parked outside, if a leak happens it just goes into the dirt. Main reason is don't want to waste fuel if a leak occurs. I don't shut off my diesel tractors all I need to do is forget to open it one time. Then I have a real problem bleeding the system. Stan

SnowStorm34 · Aug 25, 2016

Thanks for all the responses, this has been really helpful!

For those wanting to know more about the tractor, I've made a post about it here:
http://forums.yesterdaystractors.com/viewtopic.php?p=8084377#8084377

Dune Country · Aug 25, 2016

Neat old tractor, what power and trans?

SnowStorm34 · Aug 25, 2016

(quoted from post at 15:41:17 08/25/16) Neat old tractor, what power and trans?

Power unit is a Continental IY69 probably from an International 50-T baler. Trans is from a Mercury airport luggage tug.

If you're interested, I've made a post with more details about the tractor here: http://forums.yesterdaystractors.com/viewtopic.php?p=8084377#8084377

4wdtom · Aug 26, 2016

A "mini ball valve" from McMaster Carr makes shutting off fuel an easy to do thing. One quarter
turn on or off. A standard ball valve will work too but the "minis" are nice, I put them on
anything I work on that is mine. I hate turning the valve on most of the old glass bowl
strainers/shutoffs they either work hard or leak it seams and they take a lot of turns in hard to
reach places.

What is the Reason Behind Shutting Off the Fuel?

SnowStorm34

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RM-MN

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ohiojim

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W_B

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old

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Karl in MD

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dr sportster

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BarnyardEngineering

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Sean Feeney

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MarkB_MI

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BobReeves

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Married2Allis

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Geo-TH,In

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37chief

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SnowStorm34

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SnowStorm34

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4wdtom

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