Stihl fs250 blowing fuel out carburetor but plug is dry

pull the plug crank it with the plug hole downward no throttle no choke, to be sure all the fuel is out of the engine.. then let it site a couple hours plug hole down,,,

the lower the octane the hotter the fuel burns, the higher the octane the SLOWER it burns.. in my stihls i run low ocane and no boosters, in my race cars I ran lowest octane I could find... I am the nhra-vw points champion for 1978..
I also hold the record for all of nhra for the most points in one event...

higher octane slows the burn rate and volatility of the fuel, producing a more steady burn, like whats needed in small planes, there you want a a constant burn rate..

not sure of the age of your stihl but real old had points then they went to simple electronic then to pos electronic the go no go type, the early electronic rarely went out right dead without warning, you have spark so that shouldnt be the problem, the carb may be the one with flapper valve or the ballbearing valve or little plastic stopper, the flapper will let water through so it gets pumpout fast, the ball bearing not as well the dam stopper is even less efficient for that, .. no water they can all flood easy the spark plug get a little wet and being 2 cycle the oil shut the plug off, wont spark when you put it in of the engine has too much fuel... use either to blow it out it dries fast and you can put it back in after about 5 minutes... a trick to see if it will fire is knowings its all dry, hold the throttle full open and have some one spray a small shot of starter fluid just a spit right as you pull the cord, you should get a few hits, then you can do the choke and prime per the instructions for your model...

spark plug, air filter, fuel filter, and clean the spark arrestor

take it in for a carby rebuild
the rest is perfectly fine
if you have been using e-mix fuels , don't as it damages the delicate diaphragms in the carby

Sounds like the main jet or the diaphrams in the carburetor are deteriorated. Remove carb and soak in a good carburetor dip style cleaner and rebuild with a new kit. Also replace the fuel line and filter and use a fresh gas mix.

Model MS 181 Engine single-cylinder two-stroke Capacity 31.8cc, 1.94cu.in Bore 38mm, 1.6in Stroke 28mm, 1.1in Ignition Electronic (Breakerless) magneto Spark Plug NGK CMR6H Electrode Gap 0.5mm, 0.02in Carburetor All position diaphragm type with built-in fuel pump Fuel Tank 0.27litre Fuel mixture 50:1 with Stihl two-stroke air-cooled engine oil Catalytic Converter No Chain lubrication Automatic oil pump Oil tank 0.265 litre Weight
(dry, no bar, no chain) 4.3kg (9.5lb)

If the unit is running for a short amount of time but never gets to a high rpm then it could be that the needle is sticking open, or another carburetor problem. Might also blow the fuel tank completely dry, I have seen where the water would stay in the fuel tank even after it has been drained out. And when the tank is empty I would check the fuel filter. Take the fuel filter off of the fuel line and dry it off. IF the fuel filter is dark, like a coffee stain on white, then you need to replace the fuel filter. If it is a white color when dry the fuel filter is O.K. and the problem is elsewhere.
I would also suggest that you take it to a Stihl dealer that has a Gold Certified Technician, the technician will be able to diagnose and fix the problem. Usually in a timely manner. You can go tot the dealer that you bought the units from or you can go to the Stihl website and they can direct you to the nearest dealer.

Check the fuel filter and muffler for plugging. Check the fuel tank vent for plugging. Check the fuel lines for damage or decay. Check all of the carburetor fasteners for tightness including the mounting hardware for the carburetor to the cylinder. The carburetor does not appear to be pulling new fuel into itself after running on the initial prime. If the above hints don't help, you may have to service the carburetor. Check the gaskets and heat insulator block behind the carburetor for any obstruction/damage of the impulse passage which allows the carburetor to pump fuel. Hope this helps!

Check the muffler for plugging of the arrestor screen. If no help, check the carburetor for a hardened diaphragm or any plugging. Are you getting fuel into the primer bulb when pumped several times? Make sure the primer is pulling fuel from the carburetor by removing the line that goes back to the fuel tank and place a small cup or can under the primer port that the hose came off of. Pump the primer several times--it should push fuel out each time. If not, place the carburetor line on the other port and repeat the process. The pump must pull fuel FROM the carburetor to properly prime it. Barring a blown crankshaft seal, the engine should start. Hope this helps!

Take to a garage and you will soon find out that "bad joke" is the wrong name for this. All gas must be removed and gas tank dropped and cleaned. you can only hope that that will fix it. Fuel pump, line and injectors may also need attention.

check your muffler screen for being plugged, this will cause it to not accelerate
2StrokeJim