Chainsaw Won't Start

[drssg]

I would think this has been discussed before, but my search of old threads didn't find anything that seemed to match my circumstances.

I have a Stihl MS 290 that is about six years old. The last time I used it was during the winter, and it worked fine. Now, I can pull the cord until my arm goes numb, and there's no sign of life.

My best guess as to the root cause is that I'm an idiot. I didn't run the gas out of it last time, and I suspect it's gummed up. I've gotten lazy about this, because I've done it before, without paying consequences.

I'm debating whether I should just take it in vs. try to fix it myself. I've never done small engine repair, but I have a little bit of mechanical aptitude. Are there any fairly simple things anyone can suggest I try, before I pay someone who knows what he's doing?

 

[Egon]

Keep pulling, clean the plug, clean the air filter, put in new fuel mix, learn some new words, open the jets a touch, make sure you forget where they were set, close the jets, open them again, use the choke, don't use the choke. pull when at full throttle, pull when at idle, learn more new words, check the manual, keep pulling. It may start! Buy a bottle of Canadian Club and forget about the durned thing!

 

[drssg]

Dang! I guess I'm smarter than I thought. I've already tried several of those ideas. I'll try random jet adjustments next.

 

[dmccarty]

Well, I messed up on my Stihl 046.....

Same story as yours....

Except that I had a gallon of oil/fuel mix from last Nov/Dec. Said what the heck its supposed to have a stabilizer. So I tried it. I knew better.

Long story short it would not start. Had to pull the plug. Found out I DID NOT have a spare like I thought so I ran into town and got the LAST plug in stock.

Put in the new plug with new fuel mix and it started somewhat right up. Its still not quite right, it almost stalled out twice on me when it was ideling which has never happened before. I'll be working with the saw this weekend so we shall see what happens. Should not be the spark plug. It was a special fancy dancy $5 plug. Not the usuall $2 plug.

Need to stop at NAPA and get a few more $2 plugs.

Later,
Dan

 

[RobertN]

I would think this has been discussed before, but my search of old threads didn't find anything that seemed to match my circumstances.

I have a Stihl MS 290 that is about six years old. The last time I used it was during the winter, and it worked fine. Now, I can pull the cord until my arm goes numb, and there's no sign of life.

I just did repairs to my Dad's older Stihl 024AV. I put fresh gas in, and pulled a number of times. Pulled the air cleaner; did need some cleaning, but was ok. Pulled the plug; fairly new and a hot spark, but dry as a bone.

Pulled the fuel line to the carb; no gas... Went to empty the gas tank, and the fuel filter fell out. The filter was pretty dirty, but the worst was the feul line had rotted out.

Flushed the tank, put in a new fuel line and filter, and a new plug while at it. Runs great!

Might be worth looking at...

 

[jinman]

If leaving gas in a chainsaw could hurt it, mine would never start. I swear I never run my Stihl dry and just leave it for months. I add gas and pump the bulb 7-10 times, choke it, and it seems to always start in 4 or 5 pulls at the most. Actually it trys to fire once with the choke all the way on and then I put it to half-choke to get it to fire off. That little Stihl 029 has spoiled me rotten.

On most two-cycles, I find that they are nearly impossible to flood. If you pull the plug and it is not wet, it's probably not getting enough gas. Heck, I've poured a stream of gas right into the carburetor inlet on another old saw to get it to fire. I'd bet fuel delivery is your problem.

 

[RonMar]

Yep, plug wet or dry is usually the first thing I look for. If wet, you are most likley missing spark, or the plug is fouled or shorted(passing current but not sparking). Plug dry, and you are missing fuel. Most wedeater and chainsaw carbs these days are diaphram type and do not really keep much fuel up in the carb like the older float bowl type still seen on many lawnmower engines. It will usually evap pretty cleanly with out turning to crud inside. Adjusting the high speed and slow speed screws is probably not going to help you at this point. If it was running fine the last time you used it, leave em alone, adjusting them blindly may keep it from starting once you get the current issue resolved, and will surely mean you have to re-tune the engine after you do get it running. You said you don't have much small engine experience, and an improperly set high speed screw(too lean) can fry a 2 stroke engine, even to the point of melting holes in the top of the piston.

If you don't have a priming bulb(best thing since sliced bread for small 2 stroke engines), you can try putting a little fuel/oil mix down the carb opening with the air filter removed to get it to fire initially and help get some fuel to be drawn up from the tank into the carb. The diaphram pump in the carb draws fuel up to the carb using energy from the pulsed airstream thru the carb. Getting it to run, even a little is way more effective than the pulses generated from pullstarting. There should also be a vent pipe for the tank to allow air in to replace the fuel being drawn to the carb. It will either be in the cap, or will be a second hose in the tank that either goes into the air filter housing, has it's own filter element, or goes into the block. Make sure it is clean. Sometimes a little gentle air pressure applied to this vent(attach a piece of vacume hose and blow some air in by mouth), can help prime a finiky carb. But if they won't prime on their own, this usually means a problem with the diaphram.

Jinman described the ideal starting procedure. Full choke till it pops, then half choke for the next pull. Ususlly starts right up. I run half choke till it starts to run rough, as it warms, and ruduce choke as needed till warm.

Good luck

 

[MossRoad]

...

Jinman described the ideal starting procedure. Full choke till it pops, then half choke for the next pull. Ususlly starts right up. I run half choke till it starts to run rough, as it warms, and ruduce choke as needed till warm.

Good luck

I agree. I also suggest one very short blast of starting fluid in the carb first. If it pops you know you have a spark and it is most likely a fuel delivery problem. I have never, ever had fuel go bad in anything and I have left things for several years with fuel and they still fire up. Fuel filters, fuel lines give me more problems than anything.

 

[studor]

I have an MS290 and have never taken the gas out and it has always started using the process outlined by others. You might want to just dump out what is in there, put in fresh and check the plug -- I would not play around with the jets .

(Course -- could be you -- I have a buddy that if he gets within ten feet of a two cycle it either won't start or won't run -- over a period of thirty plus years a number of us have observed this capability in him )
I too have poured gas directly into the carb of some saws to get them going -- it works.
Failing all of the above practice that new olympic sport -- the dead chain saw toss and curseing competition -- you only win if you go back to retreive it and it starts

 

[Hookblock]

Just tell me what dumpster your going to throw it in, I don't have a 290





Trash to treasure

The Little woman went to the recycling center tonight, I had to work late. She got to the metal dumpster looked inside to put some stuff in it and saw what she thought was a stihl chain saw, and it was. So she grabbed it, Thinking we could use it for parts. We started looking it over and and didn't see anything wrong with it, pulled on it, sounded normal, checked the gas, smelled bad, replaced the the gas, cleaned the air filter. Checked the carb adjustment screws, set the carb shield to summer setting. Put the choke on pulled 2 times it popped, went to mid choke pulled 4 times it smelled flooded, flipped it to run opened the throttle pulled 3 times it took off I put a bar and chain on it and cut up a downed tree I had been putting off for awhile. The saw ran great

 

[Flatheadyoungin]

where are you located.........it can't be fixed!

lot's of advice here.....


1 put a new plug in it.....yeah, i know you can probably see fire but it seems plugs aren't made like they used to be.......i can't tell you how many times all something needs is a new plug......
(i spent 7 years working at a troybilt, lawnboy....well, just about everything dealer and work spring time rush for the 2nd oldest stihl dealer in the US......not that that matters! )

2 smell the gas, if you THINK it's bad dump it out.......put some fresh in

3 follow the starting procedures above

4 if it starts and runs, adjust the carb (that's a whole nuther post) but if you've messed with them a good starting point is about 1.5 to 2.5 turns out from closed....this'll get you started

5 if it's not hitting, make sure you do have fire with the new plug......open the choke, and hold the throttle open and spray some fuel (use old windex bottle or something) back in to the cylinder and follow starting procedures......i use starting fluid when i'm in a hurry but mainly when i'm too lazy to get a spray bottle but make sure you get some with cylinder wall lube in it...

6 get yourself a torx, 8 or 10mm, maybe a phillips, etc.......stihl is by far the easiest machines i've ever worked on....

7 get that carb off and look for any dried goo or flaky looking gas colored scale........then take a CLOSE look at the small screen filter that is pressed in to a concave hole in the carb.....you may even take your pocket knife and pop it out and be sure it's not caked up and clogged up.......then just take apart what you can, inspect your diaphragm, etc.....use carb cleaner to squirt in all the holes, etc....

8 while you have the fuel lines off, find the one that goes to the filter in the tank....put your mouth on it and blow in it slightly......remember you are pressurizing the tank, so when you let off pressure, remove your mouth quickly.......unless you like the taste of gas!

9 from here there a few other things to try but after that you get in to back crankcase seals, leak-down tests and things i don't know about......i'm just a country boy fixer...

 

[jinman]

If leaving gas in a chainsaw could hurt it, mine would never start. I swear I never run my Stihl dry and just leave it for months. I add gas and pump the bulb 7-10 times, choke it, and it seems to always start in 4 or 5 pulls at the most. Actually it trys to fire once with the choke all the way on and then I put it to half-choke to get it to fire off. That little Stihl 029 has spoiled me rotten.

Okay. . . I'm a fibber. I need to correct myself. My Stihl DOES NOT have a pump bulb. I wish it did, but it doesn't. I just choke it and pull. I was getting it confused with all the other 2-cycle engines on my other stuff. I think the Stihl is the only one without a pump bulb, but it has never needed one. Maybe because I don't use it that much and it's still practically new even though it is about 7 years old.

 

[dmccarty]

When I have had trouble with the Stihl and I have pulled the spark plug it has been BLACK. Its only happened twice but both times with old fuel. The last fuel was at least 7-8 months old. There was a little in the tank but I filled up from the one gallon container.

I put in a old plug that I had handy. It had white deposits which looked a lot better than the black goo on the plug I just pulled. When the new old plug would not start I went to buy a new plug. When the new old plug was pulled it no longer had white deposits it was covered with the black good.

My 046 does not have a bulb to start it but the Stihl brush cutter and leave blower do have the bulb.

Usually I just get rid of any gas mix older than a month or so but I figured I would just try it again since I figured the spark plug was a few years old and needed to change anyway. Now that I have been reeducated I'll just go back to no using old gas mix.

Planned to run the saw yesterday but that did not work out.

Later,
Dan

 

[drssg]

Thanks everyone for all the suggestions. My after work time is pretty well allocated for a couple of weeks, but I'll do some work on it, based on your feedback. I'll post back whatever success of failure I have.

Thanks again.

 

[RedDirt]

MY weedeater wouldn't run this spring. Has run fine for years, many years, and ran fine when I put it away. Went through most all the suggestions above up to and including tearing down/inspecting/cleaning the carb. Just ready to trash it but brought it in to a buddy's saw shop. He did some cursory checks, plug spark, etc. reassembled pulled the rope and zip, it started right up. I was baffled. The "trick" he used was to squirt a little oil into the plug hole when the plug was off. This sealed the old rings and got the juices pumping again. Easy fix for you if it works...good luck.

 

[RavensRoost]

Check your plug, if not wet then it is likely that the carb/jets are gummed up or fuel lines have leaks and/or are soft and gummy. ("Oxygenated" gas has a tendency to eat fuel lines even faster than normal gas, if you have it in your area.)

If plug is wet, confirm you have spark.

If all of above looks good, time to run a compression check, should be ~ 125 PSI or better.

RavensRoost

 

[toy]

My Troy Built pressure washer didn't want to start this spring, my wife was wanting to wash the camper down and she had pulled the starter rope several times but had no luck. She came to where I was and told me of her problem. When I went to check it out I pulled the spark plug wire and pulled the rope to see if there was an arc and there was. I then took the air cleaner off and sprayed wd40 down into the carburator and went to my garrage to get the spark plug wrench. When I got back to the washer I laid down the spark plug wrench and pulled the rope to see if it would start . It started the first crank after putting in the wd40, never had to take out the spark plug. I have had good luck using this method to start push lawn mowers, I started one lawn mower last year that had been setting for years it started just as easy. That is my method , but I enjoy reading other peoples methods of starting their equipment. If you try my method let me know if it worked for you or not.

 

[drssg]

Well, it starts now. It's a little embarrassing. I went through checking a bunch of things people suggested on this thread, and I went through the manual again.

I cleaned the air filter (didn't look too bad), I checked the spark plug (it looked OK to me), I checked for spark (realized I don't know how to check for spark. I think I got shocked a little, so I figured it has spark), I checked a screen that is inside the muffler (it looked fine).

I was going to try putting a little fuel in the carb to see if that would make it try to start. Just for the heck of it, I pulled the cord once first, a little tentatively, because I had never started it without the air filter in place. The dang thing sputtered like it wanted to start! So I went through the normal starting procedure, and it started right up. I put the air filter back on and fully assembled it, and it runs fine.

So I'm not sure what was the original problem. When I went to start it the other day, it had a little bit of gas left in it. I thought it was enough, since I just had a little bit of cutting to do. After wearing my arm out, I figured I needed to add new gas, which didn't seem to make any difference. Perhaps letting the existing gas evaporate from the carb helped me out? Perhaps when I started it the next time the better gas came into the carb?

Or maybe it just knew that I didn't actually want to do any work this time.

Thanks for everyone's comments. I feel like I have a little better handle on how it works, and I have some more troubleshooting steps at my disposal.

 

[RonMar]

When gas gets old enough, it dosn't want to burn. But it is electrically conductive. You pull enough, the plug gets coated with the stuff and shorts out(fouled plug) Then when you put in good gas, this shorted plug passes all the energy to the engine block and dosn't make a spark. The energy is still there, and you can get shocked, it just isn't jumping a spark across the gap in the plug.

To check spark, you remove the plug from the engine, and re-attach the plug wire. Then holding the plug with something non conductive, such as a dry rag, or dry gloved hand, hold the metal threaded portion of the plug against the top of the cylinder head near the plug hole so the metal plug body still has an electrical circuit. You need to hold it so you can see the plug gap between the center conductor and the tab bent over the center point. switch on the ignition and pull the cord. Wear glasses and the plug hole will blow out stuff(fuel and oil) sometimes. You are looking for a bright blue spark to be jumping across teh spark plug gap. It should be bright blue and about the width of a #2 pencil lead as a rule. It also helps to be out of direct sunlight and in a dark place so the spark is really visible..

 

[BigE_]

Although the spark checking method above will work just fine, I'm always a little cautious, because at that point I've likely got out the bottle of starting fluid, dumped in a little gas in the carb, etc. Basically, I've had quite a bit of flammable gas in the open around the engine, and I get paranoid about some of it going off with the spark from the plug. (Never happened, mind you, but still...)

To alleviate my fears, I picked up this little guy on sale for $1.99. I've only used it a couple of times, but it seems to work fine, and it is faster / easier than pulling the plug:
Inline Spark Checker for Recessed Plugs #97577

-Steve