Stihl having trouble

[Sawdustmaker]

I have a Stihl 025 that I was using Saturday. I had been using it about twenty minutes when it shut off. After that it would only run in the half throttle position. It would not idle or rev. Symptoms can be seen in the video. This is not the first time this saw has done this, before, it has eventually started working properly again
This saw has over 150 lbs of compression, I just rebuilt the carb, fuel line/filter seem to be in good condition, tank vent is functioning properly, impulse line is not blocked.
There could still be a problem with the carb or maybe something else.
What does it sound like the problem is??

<embed width="448" height="361" type="application/x-shockwave-flash" wmode="transparent" src="http://i216.photobucket.com/player.swf?file=http://vid216.photobucket.com/albums/cc242/sawdustmaker3/Lean.flv"></embed>

 

[308stanger]

Sounds to me that if all the fueling and vacuum is good then you might wanna think about checking the coil and the condenser/capacitor/ module, whichever one it has.I have a 028WB that did the exact same thing, while cold it would run great but once the motor started to really heat up, it would start shuttin down, it would run at half throttle but beyond that it was pointless. After letting it sit for a few minutes it would do fine but then start acting up again.Once the saw starts getting hot the coil or module starts to shutdown, but when it cools back down it'll run fine but then heats up, then starts to shutdown again. Try that hopefully that'll solve your problem. Oh yeah, if you can't determine which one it is, the coil is the last thing you want to try.(more expensive in my case)

 

[Sawdustmaker]

It acts the same cold. I don't think it is coil based on feel. Once or twice since Saturday i have gotten it to get to full throttle but it has quickly afterwards leaned out and died. sounds like it ran out of gas.

 

[spacemule]

Did you adjust the carb after you rebuilt it? If not, try turning the h screw out 1/4 of a turn at a time. If you can't set it with the carb, then you might have an air leak. Sounds like it's running fine with the choke on, but as soon as you hit the throttle and the choke opens, it wants to die. This means it's running too lean.

 

[308stanger]

well if the saw has plenty of fuel in it, no cracks or leaks in any of the lines, and your positive it's not in the firing, then i'm out of options, because you said it has plenty of compression, and that is the only thing i can think of that would make it run then stop, besides of course the fuel filter being stopped up or the air filter being stopped up as well, those are the only things that i know of that would make a saw do that, unless you might have got the carb out of adjustment, like spacemule says.

 

[windthrown]

I have the exact same problem with my 210. Ran great for a few months, and now it poo-poos out when warm. I bought another 250 parts saw on Ebay and I will start to swap out parts, like the coil and carb. I think it is the carb... it wants to run richer.

 

[Sawdustmaker]

Did you adjust the carb after you rebuilt it? If not, try turning the h screw out 1/4 of a turn at a time. If you can't set it with the carb, then you might have an air leak. Sounds like it's running fine with the choke on, but as soon as you hit the throttle and the choke opens, it wants to die. This means it's running too lean.

It is fixed jet :bang:

I am beginning to think it is the carb. So what do i do? I just changed seals, diaphram, and needle. What can I do next?

 

[shake5]

I bought a 250 almost a year ago. It didnt run right the day i bought it and
it still doesnt run right. It's been to the dealer three times, said they completely replaced the carb, but it still either smokes and shuts off or i have to lean it out and have the idle up so high the chain creeps and the throttle response is poor. Also occasionaly shuts off when turned sideways.
I've given up and hope to unload it and get a 260, but i hate to pass the problem saw on to someone else.

 

[spacemule]

It is fixed jet :bang:

I am beginning to think it is the carb. So what do i do? I just changed seals, diaphram, and needle. What can I do next?

Wait for Lakeside or fish to post.

 

[Erick]

Food for thought

When you rebuilt the carb did you clean/inspect the inlet needle??? Have you checked to make sure it is properly adjusted, it should be flush with the top edge of the housing.

Did you replace the fuel filter or just look at it, for a couple bucks it's best to be sure and eliminate it as a possible cause.

What about the internal filter screen in the carb?

Could there be a kink in the impulse line? It might look fine when you take it off the saw but might be kinked after everything is installed.

Check for a kink in the fuel line as well?

What is your current low speed jet setting? Is it set close to normal (1 turn out) or did you have to do something out of the ordinary to get it to run???

Just for sheets and giggles try cracking the fuel cap next time it's doing that.

 

[Lakeside53]

Sure sounds like impulse issues (impulse line, crankcase seals etc) to me.... More video would help...

If it came into the shop like that I'd check the fuel line and carb pressure integrity (pressure from tank end), quick check of the carb inlet screen and then pressure test the engine.

Your problem has nothing to do with the fixed H jet. It worked fine in the video.

Next time it starts to crap out, try flipping the choke on and off.. or my way - stick you thumb partially in the carb inlet (filter off) - if it can be kept running that way then your problem is certainly impulse pressure related.

Think of it from a service tech perspective - you bring me the saw and expect it to be fixed in a short period of time (shop time is expensive..). I can't spend three hours stabbing in the dark.. You need a logical approach and some tools... after the obvious simple things, pressure testing can quickly eliminate the engine, leaving only the carb and ignition. I doubt it's ignition. Carb: it's working fine for a few seconds, so it's just not getting recharged with gas. That circuit is simple so the problem likely lies outside the carb. Back to pressure (and vac) test.

 

[Fish]

Sounds like an impulse line with cracks in it, a quick check is to get the saw
running on the bench with all of the covers off, bar as well, and spray
around with some carb spray with a straw at the impulse line, mating surfaces
of the carb, carb fuel inlet elbow etc. If you hit the air leak with the spray,
the enine's running will quickly change, this method can be a real time saver.

That saw series has had a lot of fuel line issues as well, with bad cracking
on the area between the tank and carb, which can be seen if you bend the line, also have seen the part in the tank get so limber that the line
easily collapse/pinches, when you turn the saw on its side for instance.

If you do find cracks in the fuel lines it is wise to go through the carb
again, and remove the spring/ lever/needle and blowing out that passage,
as it is usually partially clogged. If you see discoloration or dust in the
impulse chamber of the fuel pump side of the carb, then expect a leaky
impulse hose, or seal.

 

[treeclimber jul]

I have had the exat problem with my ms200t ever since it was new jus not so bad. now it wont run at all

 

[Lakeside53]

If you had the problem since new why didn't you take it back to your dealer?

Are you saying it just wouldn't run for more than a few seconds, or you had to gun the throttle to get it to accelerate? If the later, you could have got a new carb under warranty

 

[PES+]

When you rebuilt the carb did you remove the welch plug that covers the low speed passages into the carb throat?

It acts very much like there is something under the plug that is moving around and blocking the low speed jets.

 

[Bermie]

That saw series has had a lot of fuel line issues as well, with bad cracking
on the area between the tank and carb, which can be seen if you bend the line, also have seen the part in the tank get so limber that the line
easily collapse/pinches, when you turn the saw on its side for instance.

My post is similar to this FWIW.
My 021 had the same problem, twice. Both times it was the fuel line. You have to have a real close look at it, the rubber hose gets micro cracks down inbetween the flexible ridges, it just will NOT run on throttle or idle, starts ok, runs on half but poops out when given the gas. Its sucking air in through the cracks.

Hope you have a happy ending

 

[Lakeside53]

The easist way to check your fuel line... is to just pull the line out of the tank, disconnect the filter, plug in a pressure bulb, and pump its up a few pounds.. you'll know immediately if its cracked or leaking. Use a bike pump if you don't have a bulb.

 

[Fish]

Use a bike pump if you don't have a bulb.

Is that what you use when it is limp and limber as well? I thought they had
pills for that, bike pumps went out in the 80,s................

 

[windthrown]

Sure sounds like impulse issues (impulse line, crankcase seals etc) to me....

Well, I have to to Lake here. I pulled my 210 apart and put in a new impulse line. Not easy on a 210. But... put it back together and pulled the starter cord and PRESTO! Runs like new again. The girlfriend is very pleased. She swears that the 250 is a lot heavier (go figure).

All hail Lake!
All hail Lake!
All hail Lake!
All hail Lake! :greenchainsaw:

The AS bus stop locker crew...

BTW: What's that fishey smell on this thread?

 

[Lakeside53]

Is that what you use when it is limp and limber as well? I thought they had
pills for that, bike pumps went out in the 80,s................

That must explain the bike pumps I keep getting at garage sales.. All I want is the cuffs:jester: