Stihl 410 wont start put new spark plug but no spark

dirt blower noise maker
https://www.manualslib.com/manual/1049162/Stihl-Br-340.html?page=32


good engine
good spark
good fueling, (carbs love to clog) good fuel. too, and mixed right.
Oil (STIHL 50:1 mix)

same answer for 100 years, Otto cycle or 2 stroke engines)

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...

All good answers here. If you have spark and it just quit running sounds more like water in system. The carb cleaners should help but you may need to run quite a bit through it. Remember to use care adding gasoline to avoid getting water into the tank. Also keep your tank full in storage to avoid condensation. In storing tong term add some sea foam and dump it out when you restart. Old gas turns yellow.

check for spark, check for fuel, if you have both poss pot and piston

Disconnect the stop switch to rule out a problem here, if there is still no spark with the plug out and earthed against the cylinder, then it sounds like a replacment ignition unit is required

If there is good fuel in the tank and the plug gets wet with fuel, and there is a good spark stating the obvious it should go, if not there could be a mechanical issue, piston scored, rings worn etc,

Flooded? Try a new plug, or get that one cleaned up. If it is sparking and wet, it should fire, even if it doesn't run, it should spark. Did you put the jets or the needle valves back to where they were? I think they start out at 1 1/4 turns out , then adjust the low and high. If it is fouling out with too much gas, the low speed jet is open too far.

right by the decompression valve is the spark plug. if you remove the one screw for the valve you will see that to get access to the plug is very easy,

Stihl weedeater was running and stopped suddenly. Put in a new fuel filter and cleaner air filter with soap and water. Checked spark plug and it appeared fine. Started the weedeater, ran for a second or so and stopped. Spark plug wasn't gas fouled. Could it be the carburetor needing new diaphram gasket and spring.

my son flooded out my stihl weedeater, I took it had a new filter put in and it started right up. he went to use it again and now it wont start! It sat overnight and i still can start it! Any suggestions please