After a few weeks of no use, my tiller started on the first or second pull but even after long warm up, it stalled as soon as I trottled up. This happens even on the stand with no resistance/load. The machine is not jammed--the tiller blades turn while the machine is idling. It just dies as soon as I try to work.

Hi Anonymouse:
I'd be checking to make sure that the correct fluid in the correct amount was added to the correct place.
Start with the oil. Check the dipstick or indicator level. Too much oil will stop the engine. Sometimes gas get accidently put in the oil filler if an inexperienced person is helping with the maintenance.
Gas.......... Make sure that oil was not accidently added to the gas tank. Drain the carb and put fresh gas in the gas tank.
Spark plug.;.... pull and check for fouling. Replace if not really clean. Check for hot blue spark before re-installing.
This should get you back digging up the garden very soon.

sounds like its flooding
the float needs adjustment or seat needs cleaning or replace

This happens frequently after a tiller, mower, snowblower, etc. sits for a season. Your tiller is probably flooded due to a stuck carb float. You can try a quick fix by tapping gently a few times on the float bowl, then pulling the spark plug and cleaning it with a wire brush, and then wiping it dry with a cloth. If you have a new spare plug to install, that is even better.
Try to start your tiller again, and if the same thing happens, your float is still stuck and you may need to have your carb serviced.
You can try one more alternative if you do not want to go through the bother and cost of having your carb serviced (or purchasing a kit and trying to do it yourself), but it is a 50/50 "hit or miss" sometimes it works, sometimes it don't type thing:
Drain all the gas out of your tiller. put about 2 ounces of carb/injector cleaner in the tank, and top off with gas. Give the float bowl a few taps. Now, pull the spark plug..... make sure the spark plug wire is at least 1 inch away from any metal. With the throttle set to full and the spark plug removed, Pull the starter cord 5 or 6 times (if you have electric start, crank it for about 5 seconds). You may see some vapors come out through the spark plug hole- this is OK.
Clean, install, and connect your spark plug (again, a new plug is even better). Give the bowl a few taps for luck, and try and start your tiller again. If the procedure worked, your tiller may run rough for 10 or 15 seconds (maybe even up to a minute or so... let it take its course!), but then smooth out.... if it stalls, don't worry.... Start it back up.
This will often work for tillers, snowblowers, mowers, generators.... pretty much any 4 stroke "lawnmower engine". It all depends on how badly the float is stuck after the engine sits.
You can minimize having this problem in the future (it may still happen, but less often and less severe) by adding a good fuel stabilizer (such as the brand name STA-BIL) to your gas and running for 10 minutes or so before you store your "lawnmower engine" for the season.
If you still have problems, the likely cause is a stuck carb float and the carb will need to be serviced.... but hopes are high that my solution helps!
Good Luck, and Thank You for using FixYa!

Hi Arch--
Sounds like the engine is not getting any fuel. You may need to remove and then clean out the carburetor. While it is all apart I would check that the float isn't broken or cracked. Carefully spray some compressed air through the carburetor jets and ports, as this will help you verify that all those tiny channels are open.
--Hope this helps.

Ok I have r Royobi Tiller (30CC Gas) And last year it ran fine after rebuilding the Carb. This year it was "hard starts" Idles fine, (Tiny whisps of blue smoke in exhaust with correct ratio) Even seems to run better with the choke "on" but still...at idle only. as soon as I touch the throttle...its bogs down in tune with how much gas I give it. Little throttle? Little bog down, Little more throttle? Almost stalls, a normal throttle rev? it stalls dead! Then starts right back up again in 1 pull and idles fine again!? WTF? So after cleaning a clean carb again, (twice) and seeing no change I thought I'd go look at the original diaphragm and compare it with the rebuild kit diaphragm (which is the one in the carb.) And guess what? The replacement has a larger rivet by a factor of "2". So basically it was flooding the carb, I bent the needle tang down, better but no cigar. But I could rev it half way now. A second disassemble to bend it yet a bit further and Vrooom vroom vrooom ****! So check your needle valve even though you think its 100%. (Especially if you rebuilt the carb with a kit!)

Your worm shaft or tine shaft and gear assembly are probably shot. Welcome to the club. Long live American manufacturing.

Check the piston rings and the valves. One of them is leaking.If you run the machine as is it will soon break down altogether...Lee

Clogged fuel filter or lines. Bad jetting. need carbs cleaned.

The troy bilt tiller is designed so that the engine revs up when the tiller starts to dig. If it is running just start tilling and the engine will rev as it needs to. If it won't start, get back as I can assist you with that.

The problem is that the fuel cap does not allow enough air to get into the fuel tank as the fuel is used. A vacuum is created and it stalls the engine. If you look at the cap from the inside you will see two small slots on each side of the black center piece. I took this apart and opened up those slots a little bit with a hack saw blade. This allows enough air to get into the tank to prevent a vacuum and the resulting engine stall.