So been wrestling with this issue since last fall.........hard time sorting it out.

So tractor will start and run.......backed it out and was allowing it to warm up while I hooked it to a mower.........while sitting there idling.......it coasts to a stop and dies. May or may not start again until it either cools down or rests. Sometimes full choke helps get it going......while warm?......but push in choke and it dies.

All that is with fuel tank showing 1/4 full. Dump in 5 gallons and all that goes away. Starts and runs normal. That tells me more fuel = more head pressure to force fuel down thru the hoses and filters........which seem to run fast or slow.......but run. But all fuel lines are new. Hoses, fuel filter, clean sediment bowl and screen and no sediment in the tank. Normally it runs a full stream. Normally I'd think as long as tank has fuel, it wold run. When it quit running today it was slightly downhill, so what fuel there was in there was over the drain. It was not empty.

Any chance something is off in the carb? Like a float or something?

Don't think there is a stand pipe in the tank. No sediment and no "bean" or whatever it is that accumulates in there to block the hole.

The fuel lines may "droop" an inch or so below the fuel fitting on the carb. This is same setup it has had since I took over and it never did this before.

The odd thing is when fuel gets down to about 1/4 tank.......it runs at idle......then just dies and will not start again until it cools down. But will then start again. That may be time to cool down or it may be time for fuel to fill carb bowl again. Something not right about a gas engine that when warm will start and run with choke, but dies when choke is off.

The little gremlins will drive you crazy.  I would take hose loose from carb, open sediment bowl petcock and drain tank into a gas can.  Then take sediment bowl assembly off, and check it over.  Also check tank for dirt.

Good Luck,

Bob

I suggest doing a similar test: put the measured 5 gallons back in the tank.

Remove the drain plug at bottom of carb, let it run out and collect.

Start a timer on the drain.  The 5 gallons should all drain in 75 minutes or less.

This lets you know that the float and needle valve have the capacity to support

your 40hp class gas engine. 

Unless the float setting is way off, there must be be an obstruction ("mo'dirt") in the main jet circuit. OR in the elbow passage just above the needle.

Running better with the choke means you are restricting air supply, which means the carb is not passing enough gasoline. Cutting air betters the air fuel ratio and it runs better. If your fuel is contaminated with a high concentration of diesel, you could have similar symptoms. That's all I know.

You have a fuel delivery issue somewhere there. I remember the story about the dead bumblebee floating around in the tank and every once in a while it would block the outlet to the sediment bowl and shut down the Tractor.  Wait a little, Tractor fires up and runs again for a short period of time and shuts off again.  Goofy stuff happens. And you wonder, how did that damn Bumblebee get in there!! 

Steve@B&B

I have had wasps in my D17 gas tank blocking the gas discharge from the tank, and the only way i could think of was they went into the gas nozzle of the hose on the storage tank and when I put gas in the tractor in the insect went with the gas.

That would be great in a perfect world, but in reality, a lot of these old tractors have some loose rust in the gas tanks, that can't be easily cleaned. It's a lot easier to change a fuel filter than it is to clean a carburetor.

There are a lot of old tractors with some sort of added fuel filter.

I included a NAPA inline metal fuel filter between sediment bowl and carb. When you disconnect the fuel line, it runs a full stream. That has been on there since I took over stewardship and has never caused an issue before. Have baled hay with it running at RPM engine speed and never missed a lick.

Will look hard to see if there is something floating in fuel tank. Have looked before, but will look again. If nothing still, I"m considering pulling the carb to have it rebuilt or gone over. Did that about 6 years ago.

BTW, normal practice when I put her in the barn for any period of time is to shut off the fuel at the sediment bowl and let her run it dry. Stored with no fuel in carb.

Do a good clean out on the fuel tank and the problem goes away.  Have done all of mine.  No inline filter, sediment bowl is clean as a whistle, no stand pipes, no running issues.

An inline filter masks the problem, it does not eliminate it.

As steve said... it dies with a 1/4 tank and runs fine with 5 gallons.. You have a FUEL FLOW PROBLEM... You would not expect to see the above in the carburetor.. You would expect it to be in the sediment bowl / stand tube / feed hose... Once it is in the carburetor bowl, it should make no difference what the tank level is.

The scenario of an inline fuel filter with a psi requirement that might prevent flow when tank is low, but works when tank is 1/4 tank or more makes sense and is consistent with the behavior. Don't remember seeing any specs to outline psi or none on the box the filter came in.......but may still have that box......or one like it.

If there is an option for gravity flow only inline filter, can try that.  As far as I know, fill cap is original. But can try that too. Almost certain tank is clean and free of any debris or sediment. That was the first thing I checked.

If something off in the carb, would think it would never run right.

Disconnect from where?   After the bowl assembly or right from the tank? After the filter?  If you eliminate potential blockage spots one at a time you may be able to at least narrow down your suspected areas if fuel flow is your thought.

I had a tiny piece of thread sealer that was creating issues with my carb float and needle. It was a tiny string like piece that would spiral/float and then get caught..  quite the interesting  find.  

Good luck!