Stihl chainsaw starting and running problems

[Jim Almquist]

I have a 031 Stihl that has worked fine until last year when it all of suddenly started to run bad and killed. I was able to restart but it seemed like it was starving for gas cause it needed choke but it was warmed up and when it did start it would die when you gave it any gas. I brought it in and they replaced some parts ( thought it was the needle and seat ?)I started it when I brought it home and it started and ran fine but I did not really give it a through work out so I was going to cut up logs around the cabin a it acted the same way so I bring to a different shop because of the hours of operation and these guys are Stihl dealers. I get the saw back and now I go out and start cutting some logs and after about 10 min. of steady cutting the saw stops and act the exact same way like it is starving for gas. I am [PoorWordUsage] about the whole thing so I put it in the garage and the next morning I thought I would start it up to see if it would run and it ran fine but I did not try any logs just revving it up. Is it a case for vapor lock or is there something that these shops are missing ? Both shops have incompetent service people ?

[goblueM]

Yeah we have a bunch of Stihl saws in our shop that are 10-20 years old and have a ton of hours on them. Sometimes they are just touchy like that when they get older and have been used a lot. Many times they will run fine for a while then die. Or only start and run when it is in full choke position. They've been taken apart countless times and put back together again, eventually they all end up doing the same quirky things. Even after being taken in to be serviced. I can't speak to the exact nature of the mechanical problem, but I've found when similar things happen (especially when it dies when you hit the throttle) just put it down for 2-5 minutes and she'll start back up again.

[eurolarva]

How fresh is the gas you are using? My two stroke gas cans used to be all different ages. Chain saw gas 3 yrs old, Weed wacker 1 year old, Ice fishing Auger 1 year old till I switched everything over to amsoil sabre. I go through a gallon every 3 months or so. Even then I always buy gas from the same gas station. If you switch different stations use different additives and by mixing these gases you get what looks like a sludge. Try getting all the old gas out and mix fresh and see if that helps.

[Jim Almquist]

eurolava I am sold on Amsoil Sabre so I try to only mix a gallon at a time just to keep the gas as fresh as possiable and only use non_oxy so I don't think that is the problem but I might just dump the rest in the rider and mix a new batch just to see if there is any change but it really seems like the thing is just Fussy We will see.

[gunflint]

If the carb kit isn't working, I'm guessing it's time for a ring and a piston. Or a new crank. It may be a good time to upgrade to a new saw.

[Eric Wettschreck]

I've had this problem, not with a stihl, but a 2 stroke motor is a 2 stroke motor.

Turned out on mine it was the diaphram in the fuel pump.

[fishermatt]

Have you cleaned the air filter recently? I have a pretty new Wood Boss 027 and it acted similar to what you're describing. I cleaned off the air filter with gas, let it dry overnight, and now it runs like a champ.

[DinkADunk]

I had the same problem with my Stihl weedwhacker this weekend. I'm also using Amsoil Sabre Professional and non-oxy gas. Anyhow, if you mix a fresh batch add some Stabil. I would also give the carb a shot of Seafoam DeepCreep as well as the cylinder and let it sit for 5 minutes or so. Start it again, let it caugh and spit for a couple of minutes and it should run fine.