1950 Farmall Cub doesnt want tostay running

Hi new to the forum and just acquired a 1950 Farmall Cub that the previous owner couldn't get to run this year. The PO had a mechanic to install a new Zenith carb, new coil in the magneto, points, plugs, distributor cap as well as clean the gas tank.
He used it for 2 years but couldn't keep it running this year.

My son and I took the carb apart and it did have some trash in it but looked good other than that. We sprayed it with carb cleaner and put it back together.
the gas in the tank had a bright yellow tint to it and left a bright yellow residue in our white drain pan so we dumped the old fuel and rinsed the gas tank out. We did not try to remove the sediment bowl because it appears to have been repaired where it threads into the tank. Perhaps soldered or welded in place. We did remove the sediment bowl screen and spray it out with carb cleaner.

We took the plugs out and cleaned then with carb cleaner as well ad re gaped them. My compression gauge would not fit in the large holes but each cylinder appeared to have suction and compression when putting your finger in the hole and spinning the engine over.

The coil wire and #2 plug hole on the distributor cap appeared to be discolored so we used a 30cal gun cleaning brush and got it back to copper color. The coil wire didn't have an end on it, just the wire bent over, we fixed that.

We static timed the magneto and connected a lawn mower gas tank to the fuel line and the tractor started right up and ran great. WE let it get hot and adjusted the carb. WE started it several times that day and let it run.

Today we put the gas tank back on and added gas. The engine started right up and ran just a few minutes and died. It fired a few times after that but wouldn't run but a few seconds.

When we disconnected the fuel line from the carb it appeared to have good fuel flow.

i am going to hook up the lawn mower tank again tomorrow and see if it will start up and run...

Any ideas?

When we had it running the other day, we engaged the mower deck a couple of times as well as well as moved it a few feet back and forwards but didn't drive it around. WE could move the throttle from low to high and back to low and it did great without trying to stall.

the sediment bowl is staying full though it did seem like it was a little slow to fill up today when we first turned the gas on and the bowl was empty.

Thanks
Anna

The drain plug on the bottom of the carb is a better place to check for fuel flow.

Try it with out the cap on the tank if runs change cap. If same then restriction in sediment bowl on tank. Might have got some solder or whatever was used on the sediment bowl partially plugging hole from tank.

There is a brass "bolt" on the bottom part of the carb that has a hole up the stem of the bolt and then across it. Run a thin wire up into the holes to make sure they are clean.

Maybe clogged in sediment bowl- since it ran good with the lawnmower tank. Use a coat hanger wire and run up through it.

Thanks for all the replies. followed everyone's advice as well as took the carb back apart and sprayed it out with carb cleaner. That was a mistake! The carb cleaner caused the rubber tip on the end of the needle valve to swell up and the needle valve would no longer open.
Not sure if i stated in my original post but the PO had put a new carb on after an unsuccessful attempt at rebuilding the original carb. It still had the new parts in it so I swapped the needle valve, seat, and float. I put the carb back on and connected the lawn mower gas tank and the tractor started and ran great.

This time I drove around for about 30 minutes. It only died once and that was when I let the clutch out too fast while trying out third gear.

Next we connected the tractor gas tank and the tractor started right up but died after idling a couple of minutes.

The sediment bowl fills real slow and appears to be seeping gas from somewhere on top of the die cast metal, not the glass bowl seal. Its not the line fittings, cut off valve, or where it threads into the gas tank. I will try to check it again tomorrow but as of now it appears there must be a crack or tiny pin hole in the die cast part. It is not dripping gas but just enough to where it evaporates before it makes a drip.

There is defiantly some kind of repair around the female threads on the bottom of the tank. I was thinking, the sediment bowl is die cast co it can't be welded as far as I know.

I guess the next step is to remove the gas tank and try to get the sediment bowl off and replace it. I guess there are still places that can repair gas tanks if there is a problem getting the new one to seal?

I guess we will know more when I get the old one off...
Any other ideas about this?

Another note is when i turned the gas on, the sediment bowl filled really slow and (difficult so see really good) appeared to have air above the strainer screen, at least after I watched it fill up.

Thanks
Anna

So far your description makes it sound as if there may be some rust or similar in the inlet of the sediment bowl.

I agree it is probably partially clogged up. The PO said the tractor was given to him and had been sitting in a barn for years. One of the first things he had to do was have a shop clean the tank. There is no rust inside it that I can see though there are discolored grey spots here and there.

The PO said he was not a mechanic and paid a shop to do most of the work. I found a couple of things that the shop was supposed to have worked on that I am not happy with. One being that the sediment bowl does not have the screen sticking up inside the gas tank. There is a mom and pop auto parts store just up the street from me and he has some tractor parts. He had the cork gasket for the sediment bowl where the glass bowl mounts. He said he probably has a new sediment bowl. i am just afraid what might happen when I try to take the old one out...

You sure the gas cap is venting?

had the gas cap sitting on top loose.
Did about 4 hrs grading with the cub between today and yesterday using the lawn mower tank. The Cub did great but wold run out of gas pretty quick. Would add more gas and it would start right back up.
I left the mower tank hooked up last night and the tractor started right up like it should except,,,,, I have noticed it starts bets without using the choke. It tends to flood out if i use the choke unless it has ran out of gas. Then it needs the choke pulled out for just a second then right back open.

So I guess its back to the strainer. Instead of trying to remove it from the gas tank, thinking, perhaps i could get the tube from the carb cleaner turned up inside the strainer port and force any trash up into the tank.
I did spray it out when we had the tank off of the tractor.

Am thinking... I bought a new gasket for the strainer bowl and there is still a slight leak but i can't tell exactly where its coming from. Its minor and evaporates before a drip forms. If the housing is cracked or the bowl has a slight leak, perhaps it is sucking air instead of gas?

I guess i need to just try to remove the strainer assembly and see what happens. The shop up the street has a new one in stock...