How To Repair A Stihl MS250 That Won't Start

[@ShannaMccormick-nc3cq]

Thank you for this video

[@austinado16]

Happy to help! Thanks for watching, and for the comment!

[@NateSobie15]

This is a great video. This is also the one I have. Which is differ t than other ms250. Ours don’t have the built in compression valve. So how do you decompress this exact model? I can pull the ripcord with the spark plug out but as soon as I put the spark plug back in even just a hair I cannot pull the ripcord whatsoever.

[@austinado16]

I just pull start the saws. I don't use the decompression valves, even if they have one.

[@keyboardr4him1]

Thank you for this video! I wasn't sure how to get to the needle valve. Your video was a great help! Mine was clogged. Once I sprayed carb cleaner through it, it blew the blockage out. Now it runs great! This is the 2nd carb my 250 has had. I love the saw, but it does have carb issues. My dad has the same saw, and he had to replace the carb after just owning it a month. Thank you!!!!

[@austinado16]

You're welcome! Glad the video helped. 3 suggestions: -If you're using Stihl MotoMix fuel; stop. Motomix contains chemicals that destroy their carburetors -If you're using ethanol based automotive fuel, mix it with Echo's Red Armor oil, and add SeaFoam to your fuel can in order to keep the fuel from chemically failing after 30 days. -If the saws are uses seasonally, or are going to be left unused for more than a few weeks, purchase a quart of Echo's non-ethanol based Power Fuel; drain the fuel from the saw's fuel tank, pour in a few ounces of the power fuel, start the saw, and run it for a moment, and then store it like that. You'll have non-ethanol based fuel in the fuel lines and carburetor, and you'll stop having carb issues.

[@keyboardr4him1]

@@austinado16 I absolutely AM using their Motomix. I wonder if that's why my dad's MS250 failed also. Thank you for the tip! I'll definitely switch it up.

[@austinado16]

@@keyboardr4him1 That's your problem then. That stuff is nasty, just smell it. Smells like turpentine and pain thinner. I see this issue (the use of Motomix, and dead carburetors) frequently. So much so, that my check on a non-running Stihl, that's a homeowner machine, it to check the fuel in the tank. If it's green and smells like paint thinner, my diagnostics are complete, and the machine simply gets a new factory carburetor... and I recommend as I did above for you, that Echo Red Armor is used, and the machine is stored with Echo Power Fuel. Future problems; solved.

[@RyanMcCue-og2xh]

I have an MS 250 that won't start. It sat for a long time but I stored it with no fuel. To be thorough I used your video to replace the carb, and I also swapped out the plug and coil. Gapped the coil with a standard business card. Inspected the fuel line and added fresh fuel then buttoned up the saw. It still won't start. Any thoughts as to why?

[@austinado16]

The fastest way to get any engine running, whether automotive, or in a piece of power equipment, is to first diagnose, in order to determine what has failed, and repair or replace as indicated by the diagnostics. In addition to that, OEM parts must be used. If chinese replica parts are used, the common result is that the engine won't start, and the person then is left wondering why, "...because I've just replaced X-Y-Z, so I know it can't be them." I'd suggest performing the diagnostics to find out what the problem is.

[@dustinadams890]

Mine has been nothing but a headache

[@austinado16]

@@dustinadams890 That's too bad, because the MS250 is an outstanding saw, whether used commercially, or not. The issue that I see with all types of power equipment, year round, and all of the time, is that the owners are using ethanol based fuel, and that fuel is left in the machine(s) and in the gas can. Even equipment where the owner states that they "run it out of fuel before storage" or "I don't keep fuel in it" are suffering from the same damage and issues. Ethanol based fuel chemically begins to fail after 30 days. That's 30 days from the time it's purchased, not 30 days from the time it gets poured into the equipment, when the reality is that the fuel has been sitting in a fuel can for X number of months. Owners don't seem to have a grasp on that. Owners also don't seem to understand that running a machine until it dies from being out of fuel, doesn't remove 100% of the ethanol based fuel from the machine. So the entire fuel system, including the carburetor, still has rotting ethanol based fuel in it. The chemical degradation rots rubber parts, and corrodes and clogs metal part. There's also an amount of electrolysis that occurs in the carburetors, because they are made with so many different metals. Best thing you can do for your saw is to do a compression test and confirm it actually has good compression, and hasn't been cooked on the exhaust side of the piston, either by running it with a dull chain and forcing cuts, which overheats the piston, or by running it on cheap, or low ratio mix oils. Shine a bright LED pen light into the spark plug hole and look forward at the condition of the cylinder wall above the exhaust port, even if you do find that you have good compression (above 125psi). If all that checks out, if it were mine, I'd replace the carburetor with a factory Zama carb, replace the fuel lines, and the fuel filter, and of course the spark plug with an OEM NGK plug, fire it up, adjust the carb, confirm oiling, and put it back into service. If it wasn't being used every few weeks, I'd only run Echo Power Fuel in it, which comes pre-mixed, and is ethanol free with a 2yr life span, once the fuel can is opened. Stihl MotoMix destroys carburetors, and Stihl won't address it. Could you still have leaking crankcase pan and crankcase seals? Sure, and you can peak in past the flywheel and visually determine that, as well as do a vacuum and pressure test. Could you have a leaking pulse hose from carb to cylinder? Sure, and again, you can inspect and test for that.

[@donbryson7895]

Great video!

[@austinado16]

Thank you Don!