Stihl MS 290 No Spark

[etbrown4]

I see no spark on the plug when I ground it against the carb, and pull the rope.

I've tried 2 plugs.

I have the choke in the 'full choke' position.

I have the chain brake 'on' or thrown forward.

Shouldn't you be able to see a spark when pulling the rope?

What is the next step?

Any tips are appreciated.

 

[jeeptj19992001]

will not spark against the carb, try the cyclinder

 

[etbrown4]

The spark wire is short.

Not sure how to ground to the cylinder, but then I would not be able to observe it.

Any suggestions on how to see the spark would be appreciated.

 

[Whiskers]

Ah yes, the previous poster gave good advice, try grounding against the cylinder.

Pull off the recoil cover and check out the ingnition coil. More specifically the wires running from the coil to the switch. Sometimes they will get damaged and ground themselves to the case making no spark. Look for rubbing and exposed wires. Also, you can remove the black wire from the coil and try the same spark procedure you already tried, if it sparks with the wire disconnected, you've got a bad spot in the wire somewhere. If wires look good and still no spark, you might want to regap the coil to the flywheel. If none of this results in spark. You might have a bad coil.

 

[fearofpavement]

provide a little more info please. ie, was the saw running fine and now won't? Did you acquire it already broke?
Have you tried a different spark plug? (edit, sorry, I missed the part of you trying 2 plugs)

As already stated, you may not have a good enough ground for it to spark. Try touching the base of the plug on the cylinder somewhere. (be careful if you have a lot of unburned fuel around the saw that you don't make fire...)

If you still don't have spark, make sure that the metal clip inside that spark plug boot is there. And also trace the wire from the switch to make sure it hasn't fallen off and shorted out the ignition.

 

[sachsmo]

If you want the quickest check.
Turn saw on, grab plug in your hand, then give it a good pull.

You will find out real quick if you have spark!


Welcome to the site.

 

[etbrown4]

Thanks to the great responses, I have found that sure enough, I do have spark.

To see it, I had to take a piece of copper wire, wrap it around the base of the plug and let the other end contact the head. Bingo, plenty of spark, though it's yellow.:smile2:

Now, the plot thickens. With 'ether' shot into the cylinder or through the carb, I am getting zero firing in the cylinder.

I've worked on lots of different motors including thousands of hours flying and working on 2 cycle ultralight airplane motors.

For now, I'm stumped. How can you have fuel and spark and no fire?:frown:

Is this unique to a Stihl, because I can't recall seeing this before and that covers 50 years of twisting wrenches!

 

[BigMoneyGrip]

You can have all the components, but if it happens at the wrong time, it won't run. Check your flywheel key if all else is in order.

 

[Fish]

Might just be real flooded with bad gas.

Why don't you give us some backround.

Was it running and died? Did you loan the saw out, just get it back? ETC??

 

[PogoInTheWoods]

Welcome aboard.

Any type of starting fluid besides 2 stroke mix for a prime = bad. Don't do it.

As mentioned, more info on the saw would be helpful in further assessing the problem.

Does it have any compression?

Poge

 

[etbrown4]

Unfortunately I have no history on this saw as it's a hand-me-down.

It appears to have had only moderate use.

The compression is 110 lbs.

At the rate your great tips are coming, we might have this solved by dinner!

Thanks

 

[Jed1124]

Sounds low on compression. I'd pull the muffler and check for scoring.

 

[Whiskers]

110 isn't great compression, but should certainly run. I'd check to make sure the muffler isn't all clogged up, paying close attention to the spark screen. If you've got weak spark, it might not fire either.

 

[abureels4me]

Here is the way I start to isolate problems
check for spark (which you have done already)
choke it and pull about 5-10 times if it hasn't tried to hit I pull the plug and see if it is soaked in gas if the plug is dry it is a clogged carb or some other fuel supply issue bad line filter etc.
If the plug is wet then I usually change plugs I have had quite a few plugs fail under compression
depending on the results of these steps determines where I go next.

 

[etbrown4]

It's running and it started about 5 minutes before dinner or 5:55 !

The tip regarding the yellow spark created the opening.

The prior owner had the wrong plug in this saw. Some knucklehead had the gap set at about .040 vs. ,020

The right plug fires with a white spark!

Now since you folks were so helpful on problem#1, here is problem #2.

There seems to be a little damage at the far end of the bar.

I don't know if this can be serviced or not. The far end is opened a little more than it should be. The tiny sprocket won't move. I'm guessing that there are ball bearings that the sprocket rides on, and as best I can tell, one of them is a little out of place.

Is the bar tip serviceable and can you replace the tiny sprocket, and re-rivet it?

Thanks, to all!!!!!! :smile2:

 

[etbrown4]

I see this on ebay:

"NEW STIHL Chainsaw Bar 3/8 375 Roller Nose Tip Sprocket for $15."

How do you determine what sprocket is needed for the MS290?

Thanks

 

[fearofpavement]

Yea! Running is good!

Now to the other question. If your bar has a replaceable tip it may be worth changing out the tip. The replaceable tip is not just the sprocket but about the 5" long nose of the bar that contains the sprocket.

Now regarding bars, There are three issues to keep in mind. One is the pitch of the chain (spacing of the drive links) The gauge (width of the groove in the bar) and then of course the length of the bar will determine how many dl (drive links) you need on the chain. ie, the length of the chain.

The saw clutch will have a sprocket with a certain pitch set up. You can run a different length bar and gauge of chain as long as the pitch is the same. If you want to run a different pitch, it will require you to replace the sprocket with one of the desired pitch.

So, the saw, bar and chain must all be set up correctly (match everything)

If the bar is messed up, just replace it. they can be had inexpensively. (or for a lot, depending on what you want)

 

[russhd1997]

I see this on ebay:

"NEW STIHL Chainsaw Bar 3/8 375 Roller Nose Tip Sprocket for $15."

How do you determine what sprocket is needed for the MS290?

Thanks

The MS290 can have either a .325 or 3/8" chain on it. It most likely has the .325 which is the standard size for the saw. The bar should be stamped with the pitch, .325 or 3/8 and the bar grove width, .050, .058 or .064. If the bar has a replaceable tip you will need those numbers to get the right one. You will also need them if the bar needs to be replaced.

 

[etbrown4]

Don't know if anyone can help me figure out exactly what I have but here's what I have discovered so far:

The drive sprocket has 8 teeth
The bar sprocket has 11 teeth
The bar groove is .064"
The bar length overall is 23 1/2"

The tip to tip distance on the bar sprocket teeth is approx. .60"
The exact distance from center to center on the chain is .653"
If you divide this by two, then the pitch is .325" ??????

Stamped in the bar is: 3003 002 70__________ GH
the rest is gone!

The tip is not removable, but you can drill out the bar sprocket.