Chainsaw

[Non-farmer]

Make sure your fuel line to the carburetor didn’t deteriorate. Has happened to me.

I've had to have my fuel line replaced 3 or 4 times. My solution was putting in a real house, deciding not to deal with the mess of a wood stove, and putting my saw into retirement (MS270).

 

[PJH]

I think I need a coil for my MS290 saw. I was sawing the other day and it died/ran out of fuel. It was out or close to it on fuel so filled it back up. Have not been able to start it since. Used the other saw to finish up that day. IT would not spark when I tried it so disconnected the kill wire from the tab on the coil. IT then would spark. Spark seemed even and regular not sporadic. Cleaned it up some pulled the plug and scrapped it off with a very small screw driver to clean any debris on the plug. After disassembly of the saw today and cleaning better cleaning all connections except behind the flywheel. Looking at the wires I did not find any bare or frayed wires. I now have good looking spark on a regular interval is a bright blue one has gas/fuel and seems to smell in the plug hole when checking for spark. Still no start. Thinking maybe the coil or plug is going bad or is bad.

My Honda generator would start first pull, run exactly 4 minutes and die. After cool down, same story - start, run 4 minutes, die. Had to be the coil, I said. Replaced the coil. Started first pull, ran 4 minutes and died. Darn!! Replaced the spark plug and it has ran perfectly ever since. You know what really griped me? I had to wait about a week for the new coil to arrive, and I had several brand new spark plugs in the drawer the whole time that I was waiting.

 

[UncleTom]

If it has spark, im leaning towards its not the coil. I would snag the fuel filter out of the tank with a hook and spray\clean it with some brake clean. Then retry it. I have fixed many that way.

 

[Earl Grey]

Always have a new sparkplug available for troubleshooting, you can't tell a plug by looking at them, and they will fire in the air but not under compression.

 

[caterpillar guy]

Saw update I put a new plug in it dealer was about the cheapest place and was an NGK plug. Still no start so I guess it must be the coil though I get a good blue spark from both plugs with it. I pulled till my arm was sore with both choke on and off .No gas appears to be on the plug nor smell in the plug hole though it would not need much. When I pull the carb off I get a splash from the one hose going to the left side of the carb. I believe it is the pulse hose not sure nor just what a pulse hose does. Not even sure if I want to spend the money for a OEM coil at almost $80.00. Not a carb guy so not very interested in getting in to that. In all of this when I had the thing all apart to check the wires I had the filter out of the tank and could blow through it backwards pretty easy for a filter all gas. So I guess I'm down to the coil or a fuel problem and not sure which for sure. IT would not pop with some starting fluid sprayed on the air filter nor at the hole for the plug. I could buy a cheap online coil and see if it made a difference. 15-20 is better than 80 to find out it is a fuel problem. I had the fuel line out and it looked alright when I had it all apart also .I did not try to blow through it nor pull air through it since it was all gas at the time. As said before in this response I did wipe the fitting off on the filter and could both blow and suck air through it. It did not look dirty nor was there crude in the tank when I dumped it out.

 

[kevinj54]

Squirt some gas through the carb & try it.

 

[OliLt]

I am not a pro, but I do maintain my own equipment, mostly Echo. I had an Echo blower that would not start despite having spark. It turned out to be the coil. The coil somehow failed and became out of time. It produced spark, but at the wrong time. Replacing the coil solved the issue. As previously mentioned, make sure the flywheel does not have a broken key allowing it to rotate on the crankshaft causing the spark to be out of time. If it will not start and die with starting fluid, I would make sure your flywheel key is not broken, and replace the coil. I replaced mine with an aftermarket coil without issues.

There are other issues that could cause your problem: low compression, or leaking crank seals. If these are beyond your diagnostic capability, it might be time to take it to a dealer.

 

[farmersamm]

Or...................you can diagnose your saw like a BOSS.

 

[Jack345]

I think I need a coil for my MS290 saw. I was sawing the other day and it died/ran out of fuel. It was out or close to it on fuel so filled it back up. Have not been able to start it since. Used the other saw to finish up that day. IT would not spark when I tried it so disconnected the kill wire from the tab on the coil. IT then would spark. Spark seemed even and regular not sporadic. Cleaned it up some pulled the plug and scrapped it off with a very small screw driver to clean any debris on the plug. After disassembly of the saw today and cleaning better cleaning all connections except behind the flywheel. Looking at the wires I did not find any bare or frayed wires. I now have good looking spark on a regular interval is a bright blue one has gas/fuel and seems to smell in the plug hole when checking for spark. Still no start. Thinking maybe the coil or plug is going bad or is bad.

I have a MS290 and have replaced fuel line & the fuel pump line 3 times due to air leaks. the AV movement of handles will cause them to leak.last problem was when setting dogs into log & getting rpm up the engine would die ran fine at idle & low/med/ high with no load rpm but as soon as trigger handle was lifted it would start to die.small hole in fuel pump line would open up with movement of AV system . And if your MS290 is older check out the AV motor mounts as they become out of round.

 

[stevieb49829]

With all that has been stated so far, pull the recoil cover and shine a light on the flywheel key slot. Look to see if the flywheel key is still lined up in the slot. Then check to see if there is the proper clearance between the coil and the flywheel. On most saws that is a business card slipped between the flywheel magnets and the coil.

Are you using non-ethanol fuel? Any ethanol in the fuel will destroy the fuel lines of an old saw and may plug up the carb with gunk from the lines. It also is hard on the carburetor diaphragms.

If you still aren't getting a wet plug, you are likely looking at a carb kit, and/or new fuel/impulse lines. Squirt some gas into the throat of the carb, with the air cleaner off (do NOT use ether). If it tries to start and run, I'd suspect the impulse line between the base of the cylinder/crankcase and the carb. The impulse of the piston going up and down in the crankcase runs a diaphragm fuel pump as part of the carburetor. I think your Stihl uses a separate rubber line. On some saws, the connection to the crankcase impulse is through passageways in the intake manifold. A kit will come with new diaphragms and flap valves to fix any of those internal problems.

PS: I sent you a "conversation" with some additional information. steve

 

[Indiana George]

Saw update I put a new plug in it dealer was about the cheapest place and was an NGK plug. Still no start so I guess it must be the coil though I get a good blue spark from both plugs with it. I pulled till my arm was sore with both choke on and off .No gas appears to be on the plug nor smell in the plug hole though it would not need much. When I pull the carb off I get a splash from the one hose going to the left side of the carb. I believe it is the pulse hose not sure nor just what a pulse hose does. Not even sure if I want to spend the money for a OEM coil at almost $80.00. Not a carb guy so not very interested in getting in to that. In all of this when I had the thing all apart to check the wires I had the filter out of the tank and could blow through it backwards pretty easy for a filter all gas. So I guess I'm down to the coil or a fuel problem and not sure which for sure. IT would not pop with some starting fluid sprayed on the air filter nor at the hole for the plug. I could buy a cheap online coil and see if it made a difference. 15-20 is better than 80 to find out it is a fuel problem. I had the fuel line out and it looked alright when I had it all apart also .I did not try to blow through it nor pull air through it since it was all gas at the time. As said before in this response I did wipe the fitting off on the filter and could both blow and suck air through it. It did not look dirty nor was there crude in the tank when I dumped it out.

 

[Indiana George]

Check your filter and your gas line in your gas tank ,if your gas line and filter is disconnected from the gas line it would never start

 

[SARG]

Just a thought ...... Check the spark arrestor on the muffler ....... they become plugged with soot and create the no start condition you describe.
Plenty of YouTubes on the condition & repair.

 

[caterpillar guy]

Well now an update on the saw. New coil and gas through the filter and straight in the carb and no start key is not sheared nor gas in the plug hole still not start. Compression is at about 50-55 by gauge. Should still start though. Gas is not as pristine as I might like but is working fine in 3 other saws. All start and run fine with it so I'm ruling out the gas also tried some different gas and still no start. Spark is fine with both just an arc and through a spark tester. Only thing I can think of is either the carb or the line.Gas will spew out of the line at the carb when carb is removed so I'm thinking that should rule out lack of fuel to the carb. Also would think it would rule out a hole in fuel line and pulse line. Vent is open and can blow or suck air through it both ways. At a loss at this point.

 

[kevinj54]

I am not sure it will run on 50psi. Try the gauge on another saw as some gauges do not read right on a saw.

Did you try an inline spark tester to see if you loose spark under compression???

I know you said new coil but is there a chance the kill switch is grounded??

I would remove the kill wire and re-check spark.

Maybe put a bit of oil in the cylinder to lube it up & see if compression improves.

 

[Janicholson]

That compression is 50% lower than recommended minimun. It may have quit from a crank seal leak, or rings or? Jim

 

[kencombs]

I had some difficulty starting a saw a while back. It was running, but wouldn't restart after running out of gas. Probably flooded. I was reading on the 'net about the problems and read a 'trick' that got it running.

Pulled the plug, put a little (very little) oil in the cylinder, pulled it over once, reinstalled the plug and pulled the starter. Started right up.

My guess is that there was no, or little residual oil since I ran it out of gas, then maybe to much gas when restarting. The drop of oil built the compression enough to get it going.

 

[bob p mn]

Does your saw have the screen type spark arrester in the muffler? I have had a couple differant saws that acted like that and removed that screen and away they went. You can burn the carbon off and then brush them with a wire brush and put em back in. Also had the same thing happen on my Stihl weed whips when we were mowing and trimming the local cemetery and putting a lot of gas through them. I always used Stihl mix oil, the dealer said it wouldn't carbon up those screens but it did. easy fix. I would guess if the exhaust is restricted it would lower compression.

 

[caterpillar guy]

Arrester is fine we checked that screen had a couple spots but not enough to be a problem ,Cleaned it with a brush anyway. WE did check spark with a spark tester but not in the cylinder just out in the open. Will check in the hole. IS a new plug also not that it can't be bad and not that the new coil could also be bad but seems unlikely to me. And maybe it is just time to put the old girl to bed. Would like to keep it going a few more years just so I have a backup saw. New ones are so expensive and have a lot of junk on them that I hear makes for a lot of problems in a short time also.

 

[kevinj54]

Have you done the pressure vacuum tests? A leak there will not change compression but the 2 cycles need to be tight.

A leak can score the cylinder also. Crank seals & cylinder kits will be way less than a new saw.

Maybe remove the muffler & carb so you can see if the cylinder is scored.