600 only runs choked

Bought a 640 a couple of weeks ago. It ran well when I looked at it but when I got it home the carb was dripping and had been dripping for a long time as the oil filter that he previous owner painted to match the tractor had been damaged over time.
When I tried to start it the bowl was definitely overflowing into the air intake and running out there also.
Took the carb apart to check the float. The carb had a repaired spot on it and either was stuck or sunk. I ordered a float, needle, and seat and installed.
The carb was really clean, but cleaned it out with carb cleaner, replaced the gaskets and put it back on the tractor.
Also replaced the spark plugs, oil and filter.
After that it fired right up but had to pull out the choke to keep it running. Previous owner said he never had to choke it.
It will only run with the choke pulled out and stalls regardless of throttle position when you push it in.
So where do I look next?

Thanks!!

Did you make any carb adjustments?

Before I took the carb apart I checked the main adjusting needle and it was 3 full turns out. The book says 1 1/4. I put it back together at 1 1/4 but when it ran like it did a turned it back out to 3 full but no difference.

It has a TSX 428 and not a 580. There is no sediment bowl inline and the fuel line has a shut off inline about 6 inches up the fuel line from the carb. The tank is clean and there was no junk in the carb when I opened it. I did try taking off the gas cap and pulling the air intake hose off.

(quoted from post at 21:31:53 08/11/20) It has a TSX 428 and not a 580. There is no sediment bowl inline and the fuel line has a shut off inline about 6 inches up the fuel line from the carb. The tank is clean and there was no junk in the carb when I opened it. I did try taking off the gas cap and pulling the air intake hose off.

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Suspect float level set too high (from upper carb body). I'd be getting a sediment bowl back in the system as well, were it mine.

Agree with Larry.
I've worked on a several Marvel-Schemblers with good success. I also sent two of them to Motec Engineering in Tipton, IN for rebuilding and they did a super job. They test them on an engine before shipping supposedly. Mine bolted on and ran perfectly. Recommended.

Check your ignition points. Clean or replace them. Using the choke means less air gets into the cylinder and that gives you less compression. It takes less voltage to jump the spark plug gap with lower compression. When the carburetor adjustment makes no difference you need to look elsewhere for the problem.

I opened up the carb and adjusted the float level a bit. No change.
Checked the points and other than the gap looking a little wide, they were clean. I will adjust the points gap maybe this weekend. The cap condenser and coil look new.
The guy I bought it from had 10 tractors at his house. This one he said was redone 5 years ago and had only been to shows. Has 5 hours on proofmeter.
The spark plugs were dirty so he didn't redo everything.
Guess I will replace points condenser and coil next.

Only running choked indicates a fuel problem. It has nothing to do with anything electrical.

(quoted from post at 08:26:47 08/13/20)
Only running choked indicates a fuel problem. It has nothing to do with anything electrical.

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totally agree that it is a carb issue. Take a look at this carb diagram, " www.carburetion.com/CarbNumber.asp?Number=TSX-428 " Did you pull item # 24 in the diagram of the carb , that's the main fuel nozzle , the little holes are probably plugged. Also run a small wire through each of the internal passages. As a final part of the cleaning process i use a soda blaster made from a blow nozzle and small tube through each passage. A quick google of " Soda Blaster " will show you what i am talking about. In my humble opinion it is far better than and other method.

Only running choked indicates a fuel problem. It has nothing to do with anything electrical. I totally agree that it is a carb issue. Take a look at this carb diagram, " www.carburetion.com/CarbNumber.asp?Number=TSX-428 " Did you pull item # 24 in the diagram of the carb , that's the main fuel nozzle , the little holes are probably plugged. Also run a small wire through each of the internal passages. As a final part of the cleaning process i use a soda blaster made from a blow nozzle and small tube through each passage. A quick google of " Soda Blaster " will show you what i am talking about. In my humble opinion it is far better than and other method.

Thank you for the replies. I watched several videos before replacing the float, needle, and seat. Part #24 removed, cleaned, carb cleaner blown through all, including the holes in bottom of bowl. Nothing seems clogged in any way.. Opened up the carb and did it all again tonight.
Still same problem, only runs choked.
While I had the fuel line disconnected I opened the shut off and fuel runs freely.
The only thing I found based on the diagram is that below part 24 there is part 26 jet power in a and b carbs. It is missing.

I was able to find an original Marvel Schebler tsx580 from John at vintage tractors and have a sediment bowl ordered. I'm going to run new fuel line and see where that gets me.[/quote]

You may have already done this but one other thing you could try is to unhook the air intake from the cab and try running it. If it runs better you have a restriction in the air intake.

So it took over a month to resolve because I got three different banjo bolts from three sources that were threaded wrong.
Not sure why a stuck float on a running tractor turned into one that would not run right, but after cleaning the carb, rebuilding, cleaning again, I gave up and bought an original 56 MS TSX 580, original fuel line, sediment bowl, and started from scratch.
Runs great!