Stihl Easy to Start - Isn't

[Dave Fritz]

I have an easy to start Stihl chainsaw that will start but will not come up to speed. When I do try it dies.

I'm using their Motomix fuel. This is in their information: There are several things you can check. First, make sure that you are using fresh fuel mix (never store or use fuel mix older than 60 days in can or fuel tank)

I'm confused about the store fuel mix in the can. It comes in a can and it saws it's good for two years once opened. Since I use it very little should I purchase qt cans instead of a gallon.

This saw has been to the shop and allegedly runs fine. After the holiday I'm going to take it back and have them show me that it runs fine. Can't figure out what I'm doing wrong.

[John K Jordan]

Hard to diagnose long distance without more detail. How long ago since it was pronounced well by the dealer? What’s the history, did the saw run well at one time and now doesn’t? If so, did the problem start suddenly between uses, after sitting a while, after switching fuel? Does it start easily then die immediately when either goosing or feathering the throttle?

I have several Stihl saws, some in long use, one an easy start model. The biggest problem I’ve seen in other people’s saws is not carefully following the starting instructions in the Stihl manual. Assuming you are starting exactly as recommended, the other things I would check are: good spark at the plug and clean air filter. I have no experience with pre-mixed fuel, I always mix 50:1 with Stihl oil (with stabilizer), premium gasoline without ethanol. I don’t pay close attention to the fuel date warnings but that’s good advice. A few times some saws sat unused for many months without problems (not something I recommend!)

The times my saws got “cranky” about starting or running the problem turned out to be not enough spark (tested and adjusting the coil fixed that), problem with carb (bought new carb at local dealer for much less than I imagined, replacing was easier/quicker than rebuilding), adjustment screws (followed the instructions in the manual and my chainsaw repair book). Once, replacing the air filter helped even though I cleaned it regularly. Many saws have a warm/cold season mode you might check. If it has a fuel primer bulb pumping it a little extra doesn’t hurt.

I recently had a problem with a Shindaiwa Pro weed whacker where it started fine but wouldn’t rev up to full speed. After using another whacker for about 6 months I decided to fix it. After cleaning and checking everything else I was about order a replacement carb when I noticed a pinhole tear in the fuel line. Runs perfectly after fixing that.

I read once that if an engine has good compression, good spark at the right time, and a good air/fuel mixture it HAS to run, “it don’t have any choice.”

JKJ

[Jeff Roltgen]

I can relate. All I can say is, as crazy as the 60 day spoilage warning is, you really do need to heed it. Local dealer set me up with the oil to mix myself. Actually extended warranty on a new Stihl trimmer at that time, based on including a purchase of a 6 pack of their oil. I typically dump the remaining gas in my pickup tank and mix a new batch. Those little engines are outrageously fussy about fuel, and if you ignore the warnings, they eventually won't run at all.

Local service shop showed me by pouring remaining gas from an older Stihl chainsaw I was struggling with into a pyrex cup, and sure enough - was cloudy and starting to gel. I used to be able to use it, pick it back up 6-9 months later, and it started perfectly, which is why I loved it and committed to the Stihl brand. Suddenly, no amount of tweaking and tuning could bring that performance back.
They explained loosely using these terms; the VOC's used now days to dial-in the octane rating flash off very rapidly, causing the fuel to go bad.
And of course, the ever-present notice:

High Octane Premium with NO Ethanol.

All this has me reaching more frequently for an extension cord and my electric chain saw.

jeff

[Thomas McCurnin]

Stihl is a good brand. On weekends, I work for the USFS and all the forestry guys use nothing but Stihl, and using the Monomix, it extends your warranty up to 2 years.

[Tom M King]

Check to see if the spark arrester screen in the muffler is clogged up. They have to breathe out as good as they breathe in.

There is one screw holding that screen in. Take it out. If you can't easily see through it, hold it with an old pair of pliers, and heat it red hot with a propane torch. If that didn't clean it off, when it cools rub it between the fingers of an old glove.

Put it back in, and it should run like a new one. This is a regular maintenance thing on 2 stroke small equipment. On my MS180, I have to do that after about a gallon and a half of fuel. Some mixes are worse than others.

[John K Jordan]

Check to see if the spark arrester screen in the muffler is clogged up. They have to breathe out as good as they breathe in....clean it...
This is a regular maintenance thing on 2 stroke small equipment. On my MS180, I have to do that after about a gallon and a half of fuel. Some mixes are worse than others.

What could cause such screen clogging?
- Type of oil, gas, mixture?
- Carburetor adjustment?
- Type of saw?
- Frequency or type of use?

I'm curious since I've inspected my saws occasionally and over many years and gallons of fuel I've never seen even a tiny amount of buildup. (My gasoline Stihls are MS250, MS250c and MS361.)

BTW, on my smaller saws the screen is behind a plate on the front of the muffler held on by two 8mm nuts. (Tip: a bit of anti-seize compound on the threads will make life easier in the long run)

JKJ

[Tom M King]

I've never had any trouble getting the screws out, or with them staying in. I guess it's from a non complete burn of the 2 stroke oil. The 180 is particularly bad about it. My string trimmers need it about once a year. It's not unusual at all for small 2 stroke engines. The screen is a spark arrester.

The 066 is the oldest running one I have, and I've never had any issue with that one.

The symptom is the motor will start, but not want to rev up freely, and make a funny sound, often dying.


https://www.youtube.com/watch?v=EFvVFbWm6lI

[Dave Fritz]

To answer some questions: it never did work since coming from the dealer. I put on the choke, pump the bubble ten times, one pull , turn off choke and it starts but will eventually quit and will quit immediately when I give it gas to rev. up the engine. The Motomix I'm using is less that one year old and has been in the original gallon can. Last fall I ran the engine completely dry of fuel and stored it in a heated garage. This year my son in law used it and returned it. I dumped the gas he had left in the saw into my UTV and filled it with new Motomix (Seafoam added by me). It worked fine on one tree. When I next went to use it about two weeks later, no go. I dumped that fuel into my UTV and replaced with fresh. No go. I'll check out the spark arrestor screen but will no doubt take it back to the dealer. I paid them $51 and it was supposedly fixed. I do have a Stihl battery saw that works just time but has it's limits. I wonder if anyone makes a battery operated one with a sixteen inch bar? I'm about done with gas engines. At 78 there just aren't many jerks left in the old shoulder. Thanks for the input.

[Ken Fitzgerald]

Take it to the dealer and make then show you it starts easily multiple times.

[Tom M King]

That sounds like more of a problem than the spark arrester screen. One good thing about cordless chainsaws is that they are easy to start.

[Jim Becker]

Any time I've had the "starts but then dies when the trigger is pulled" issue with my MS290, it's been because i, um...tighten the chain up too much or the sprocket in the end of the bar was clogged up.

[Larry Frank]

I have a Stihl chainsaw and it works fine. If not run in awhile, it is grumpy. I have arthritis in my shoulder and starting it aggravates it. I solved the problem !!!! I bought an Ego Chainsaw and it starts with no problem. For the frequency that I use a chainsaw, the Ego is a better choice for me.

[Alex Zeller]

Sounds like a fuel issue to me. Might want to check the fuel filter. In my saws it's inside the tank and doubles as a weight to get the fuel hose to the bottom of the tank no matter what position the saw is in. Also, depending on what the dealer did the fuel line could be pinched.

[Zachary Hoyt]

Just a thought--a couple of times I have accidentally engaged the chain brake while the saw was sitting, and then it would act as you describe till I noticed and released the brake.

[Dave Fritz]

Thanks for all the input. I'm taking it back to the dealer and do as Ken suggested. Larry, I agree, my next will be battery operated. I don't use one much either.