TO-30 bogs under load

So I purchased a TO-30 last year for pretty cheap. This is my first tractor, so I purchased all the manuals to go with it. This being said, it ran flawless for a full year(minus having to replace the hydraulic piston). I got my first grading gig with it using my 5' box and got through 4 dump loads of dirt without a problem and ran out of gas. After getting new 87 octane fuel, I also added Stabil fuel additive to it because I didn't expect to use it much after the job. Immediately adding the new fuel, it began running sluggish while in gear and would bog down to shutting off when trying to pull. If I put the clutch in when it starts to stall, the engine continues to run flawless.

I took the tractor home, drained the tank and refilled it with 93 octane fuel and added seafoam to help clear any crud from the carb. Fuel bowl is clean and never any signs of debris from the tank. I disassembled the carb and cleaned it, only by removing the floats and needle, to spray/wipe clean the injector holes and bowl.
Fuel flows freely to the carb, no apparent issues there.

Onto the electrical!
I have not been able to use a "plug wire" tester, but have pull the plugs while running and have been bitten by them all. The distributor cap is only a few years old(says the man I bought it from) and the points look good. New plugs have been installed. It is a 12V system with a brand new battery and alternator.

Puzzling part: When you pull the plug wire from cylinder #3, there does not appear to be any change in engine speed, this is not the case when pulling a wire from any other cylinder.

Been trying to get this bad boy going like it needs to be. And because it's old, movable parts keep breaking. Still trying to convince the wife that although I only have $3000 into this machine(sale price included), it's more than worth it for this gem!

Any help is greatly appreciated!

You'll get smarter replies than I can give, so all I'll do is tell of my experience with my TO30. After I ran it out of gas early in my ownership I had a very similar problem. I cleaned the sediment bowl, line, and carb several times with no improvement at first. Yet in the end I got it pulling strong again, and I am convinced it was a problem in the carb, but my initial cleanings must have missed it. Leastwise, it was after a thorough final (because it worked) cleaning of the carb that it ran with power once again.

Your situation may be totally different.

I'll defer to wise minds than mine on any possible electrical components....

Since you ran it out of fuel, I"d suspect you got some crud in the carb fuel passages.
You say that you have adequate flow to the carb. Did you check the screen in the fuel elbow at the carb? Make sure the carb drilled passages are clear. You may have some crud in the transfer port (highest hole in the throttle passage) so you are overly lean when you accelerate.

Make sure that you have the correct firing order on the plug wires (1-3-4-2)and check the distributor cap #3 hole for corrosion and make sure the #3 connection to the plug Is good and that the insulator isn"t cracked on the plug.

Is the distributor bushing worn? if you push radially( from the side) the distributor shaft should not move. if there is any motion when you do this(over 0.002") You need to get it re-bushed.

Hope this helps.

I have the same feeling as what you said, maybe I will just order a rebuild or maybe find a new one for inexpensive.
Thanks for the tip!

Quick and dirty: change #3 plug out with one that does slow motor when you pull wire from it,

If the miss follows the plug, get a new plug,

if not do a compression test on the #3 cylinder, if low, then add a small amount of oil to #3 cylinder and see if your compression comes up,

No matter how clean the carb or octane level of your fuel, you must have all four cylinders hitting about even on compression to have a smooth running engine,

Were you using non ethanol fuel when you ran out of fuel? Most of these old tractors do not like non ethanol fuel.

One other option you may still have an obstruction in the carb,

I'll stick to playing with the carb more, since it seemed to happen after a change in fuel incident. Distributor itself has no movement and no issues with the wires(in the right firing order).

Also, when I changed the plugs, the #3 plug didn't seem to be burning hot like the others, maybe I'll just play with the cap some more as well.

Thanks for the quick responses fellas!

Plug test was done, doesn't change anything. Still doing a compression test soon and it's running on standard fuel.

I'm voting with Jerry/MT for a fuel/crud issue.

I had a similar problem with my TO-20, and it took about three tries of carb-cleaning to find the crud I had picked up somewhere.

After that, it starts and runs perfectly - just like it did with a freshly-rebuilt GB in MT carb!

You mentioned the manuals - do you have the Service Manual? It has a good carburetor section.

A simple and quick test of suspected lean carb problems, try partially choking when it starts to bog. If it gets better, it's too lean. If it gets worse, black smoke, it's not a carb problem. Also there is a plug in the bottom of the carb. With the fuel valve open, remove the plug, catch what comes out in a clean glass. Should get a full flow until the bowl empties out, then slow to a trickle. If it slows to a drip, there is a delivery problem to/through the carb. Look at wjat comes out, if dirty of has water, there is a contaminated tank.

The miss firing #3. When you pull the plug wire from the plug (not the cap end), can you hear a spark jumping to the plug? If so, it's probably OK. You can also try switching the plug wire from another cylinder, see if the problem follows the wire.

If the compression is low, take a look at the rockers and lash adjustment. Make sure the valves are opening, (flat cam), check for bent pushrod, broken valve spring. If you do end up pulling the head, you'll want to use bolts and washers to temporally hold the cylinder liners down. They just sit in the block, if the engine is turned with the head off, they will ride up, get trash under them, start leaking coolant into the oil. Be careful!

How is the blow-by? If the rings are bad enough to cause a miss, there will be smoke and oil blowing out the crank case vent tube.

Also before tearing it down, check for vacuum leaks. Spray Berrymans or something flammable around the intake gaskets, see if #3 will start hitting.

My problem turned out to be the valve in the bottom of the tank. I fill from a 5 gal can, somehow trash plugged (actually a wasp, don't know how he got in there) about half of the inlet to carb.

I always use a good quality fuel funnel with a small mesh screen,

Do not know how it happens but fuel transfer cans can get debris in the fuel.