"B" Starving for gas; does low gas tank level matt

Hi all,
I have a 50 B, and I just rebuilt the whole engine as well as the carb. The tractor ran really well at first, but a series of water in gas, then sediment issues led to several tank removals and cleanings. So tonight I got it all put back together, put in about a half gallon of gas, then fired it up. It ran good for a few minutes, then died. I closed the sediment bowl valve, take off fuel line at carb, open valve, and gas rushes out. Okay, I think, clogged carb. I take it off, open it up, and everything is as clean as a whistle. All the jets, everything. The carb needle and seat seem great. Is it possible that a low tank level doesn't have quite the gravity "oomph" to fill up the fuel bowl past the needle and seat?
I have to say it's surprising how small the hole is in the seat part of the needle and seat set. My cruddy tecumseh lawn mower engines have bigger through holes.
Thanks for any experienced comments!
Dave

Ahhh,
Those are great suggestions. I will put the carb back on and check the flow at both those locations. But first I have to get through a pesky work day first.

I'll post back.
Thanks,

Dave

Also if you get low flow out the main jet cap you can spray carb cleaner into it with the drain plug out and some times that will fix the problem. I have to do that on my C once in a while
Hobby farm

Ha ha, yea I know it IS spendy nowadays to put 5 gallons of gas in the thing. But I didn't want to put in a ton of gas until I get all the little problems sorted out.

So tonight I fixed the problem and it turns out it's a multi part problem.
First thing is we got a bad load of gas in the farm storage tank. It's about 20 percent water. I put some of this in the "B" last week and it proceeded to rust up the internals of the carb. I cleaned that all out and then tried the suggestions of checking the gas flow at points along the gas circuit.
The gas gushes out of the tank sediment bowl. Check.
The gas flows through the first hose sections. Check.
There was a new inline fuel filter before the carb. Bingo. Dribble-city after the inline filter. The filter is see through and looks pristine. I wonder if the fine element is clogged with high surface tension water. Not a big deal on a fuel pump vehicle, but not good on a gravity system.
So I took out the inline filter, removed the main jet plug and gas pours out nice and fast. So I fired it up and it's running fantastic again.
I'm not going to put a filter inline as I think the sediment bowl screen is probably sufficient. Now we need to figure out how to clean the 200 gallon supply tank of all that water...
So thanks again for the suggestions.

I'm willing to start the debate. Pump 20-25 gals. and replace it with like amount of E85. That should be about 20 gal of alcohol or E10 mix since E10 came out I never use HEET anymore and haven"t had frozen gas problems in 15 years.