MS290 will not start

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dallypost

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Hi all,

This is my first post here and I sure hope that you can help me.

I have a two year old Stihl MS290. It has had light use, cutting firewood and a little fencing around the ranch. Recently, while cutting up a log, I noticed that it did not have a lot of power. I only had a few cuts to make so I did those and shut the saw down. A short time later, the saw was still warm, I dumped the fuel and added fresh. The saw would start, idle for a few seconds and die. I brought it home and it has never run since. In fact it doesn't even try, no pops or sputters at all.

I have cleaned the air filter, checked the spark arrester screen and found it to be clear, replaced the fuel filter and the spark plug and replaced the fuel. None of this has helped. Is there something simple that I can try before attempting to rebuild the carb or paying the dealer to do it?

By the way, how difficult is it to rebuild a carb on these things?
 
Look at the fuel line just below the carb/air filter, it likely has cracked,
replace that and go through the carb.
 
If you cleaned the exhaust screen, pull it back out. Once you have the cover off, slide the muffler off the mounting studs, and have a look at the piston. If it has vertical scratches, you have problems.
 
If you cleaned the exhaust screen, pull it back out. Once you have the cover off, slide the muffler off the mounting studs, and have a look at the piston. If it has vertical scratches, you have problems.

would be quicker and easier to just pull the spark plug and take a quick look from there....shine a light in the hole and look at the exhaust side of the cylinder wall.... if it looks pretty good then get your self the following, your gonna need it...

Fuel line
1127 358 7702

and fuel filter
0000 350 3500

I have replaced 18-20 fuel line assembly in 290's in the last month....ALL cracked right at the bend where the come out of the tank....in fact you dont even have to take the air filter cover off to check this....take a light and look in from the side above the tank and below the air box....

Of course a real red neck could fill the saw with fuel and lay it on its side...hahaha
 
Check the compression - 1st pull circa 100psi, 5 pulls - 140psi+, if you can't do this, pull the muffler and look for the tell tale vertical scores in the piston, if you see this then you have some work to do. A basic check is to lift the saw and let it drop whilst holding the pull start, it should fall slowly -circa 8 - 12 seconds to fall.

Check the spark by removing the plug, putting the cap back on, EARTH it on the cylinder head and pull the engine over - you should see a nice fat blue spark.

Put the plug back, put the choke on and pull the saw over five times - pull the plug and check it is wet.

9 times out of 10 - if you have a wet plug, compression and spark, the engine should run.

Spud
 
Check the compression - 1st pull circa 100psi, 5 pulls - 140psi+, if you can't do this, pull the muffler and look for the tell tale vertical scores in the piston, if you see this then you have some work to do. A basic check is to lift the saw and let it drop whilst holding the pull start, it should fall slowly -circa 8 - 12 seconds to fall.

Check the spark by removing the plug, putting the cap back on, EARTH it on the cylinder head and pull the engine over - you should see a nice fat blue spark.

Put the plug back, put the choke on and pull the saw over five times - pull the plug and check it is wet.

9 times out of 10 - if you have a wet plug, compression and spark, the engine should run.

Spud

Yep. Mr. Spud is correct.... start at the beginning. Do you have adequate compression?
 
Check the compression - 1st pull circa 100psi, 5 pulls - 140psi+, if you can't do this, pull the muffler and look for the tell tale vertical scores in the piston, if you see this then you have some work to do. A basic check is to lift the saw and let it drop whilst holding the pull start, it should fall slowly -circa 8 - 12 seconds to fall.

Check the spark by removing the plug, putting the cap back on, EARTH it on the cylinder head and pull the engine over - you should see a nice fat blue spark.

Put the plug back, put the choke on and pull the saw over five times - pull the plug and check it is wet.
9 times out of 10 - if you have a wet plug, compression and spark, the engine should run.

Spud


if the saw is flooded bad enough this is a great way to get someone hurt....
 
Wow, lots of great suggestions, thanks.

I have checked most the things that you suggest, fuel filter, spark, air filter spark arrester, they are all good. I think compression is good because the saw when from very strong to very weak in just a few minutes time but I will check that.

It sounds like a cracked fuel line is common so I will check that.

If compression and the fuel line check out okay, do I need any special tools to go through the carburetor or will basic hand tools do the trick. Is there a tutorial or directions available for carb rebuild?

Thanks
 
Now I am really puzzled. I checked compression by suspending the saw by the starter rope. It took about 18 seconds to fully extend the rope. I chocked it and pulled the rope a dozen times and plug came out wet. I poured a small amount to gas in the carb and pulled it over ten or so times... nothing. Then I rechecked the plug, it was really wet.

It seems like all the necessary parts are there, compression, spark, fuel but the saw won't even pop. Any new ideas?
 
Now I am really puzzled. I checked compression by suspending the saw by the starter rope. It took about 18 seconds to fully extend the rope. I chocked it and pulled the rope a dozen times and plug came out wet. I poured a small amount to gas in the carb and pulled it over ten or so times... nothing. Then I rechecked the plug, it was really wet.

It seems like all the necessary parts are there, compression, spark, fuel but the saw won't even pop. Any new ideas?

Did you pull the muffler?

Go buy a compression tester.

Methinks you may have some cylinder and piston issues.

:cheers:
 
So let me get this straight....you pulled a dozen times with the choke on (you FLOODED IT) and then put more gas down the intake (flooding it further) ? and cant figure out why it wont fire off?....

Take it to someone who knows what they are doing....PLEASE....
 
Let the saw sit for awhile. Let all of the fuel evaporate. Go to the Sears store and buy a compression tester (one with schrader valve). While you are there buy a long T handle T-27 torx bit. You will thank me later when you need to pull the jug off to replace the piston. Now go get a compression reading and let us know what it is. Screw the tester into the spark plug hole and pull it over until the needle quits moving. I'm betting your under 130 psi. If so, read the post in my signature line on how to rebuild this critter.
 
So let me get this straight....you pulled a dozen times with the choke on (you FLOODED IT) and then put more gas down the intake (flooding it further) ? and cant figure out why it wont fire off?....

Take it to someone who knows what they are doing....PLEASE....

Don't it just make you feel good to give a guy grief on his first post.
 
Don't it just make you feel good to give a guy grief on his first post.

It makes me feel good when someone gets there equipment fixed and is back to work using it, rather than all the messing around and wasting time...in a case like this, sometimes the internet is not your freind....

the only time I check post counts is when someone makes a comment like you did...:)

Have a nice night....:clap:
 
DID YOU PULL THE MUFFLER YET AND LOOK AT THE PISTON???????

I have a box with DOZENS of scored MS-290 pistons in it. about half from straight gas, and the other half from people running with a broken fuel line. Your power would decrease in just a few minutes to where it would not run if the piston were scored. The "drop test" on the starter cord is OK but sometimes on the 1127 series, the cord is cocked such that it creates drag when you pick the saw up by it. Especially if there is a bar on there.

We need some pictures, or some actual compression numbers. Also you might want to turn it over and clear the fuel out of it. Then try starting it on the fast idle position. If there is low compression, none of this will help.
 
I'm betting on the fuel line as the first problem and then flooded. Why jump to the P/C before checking the easy stuff first? Just fixed an 029 that had very similar symptoms, just like Fish said, fuel line cracked just above the grommet out of the tank (about 1/3 hose diameter).
 
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