025 Dilemma

[woodgrenade]

I'm trying to trouble shoot my buddie's 025. It is hard to start, and once running it will not idle. It will only run at full throttle or when you you have the operator lever set at high idle. I replaced the impulse line, the carb with a new one, and swapped in a coil with one I had laying around and changed the spark plug. The fuel line and filter are not clogged, and I was running fresh gas. The air filter also is not blocked.

The saw still runs exactly the same as before I touched it. Hard to start, and will not idle on its own. The carb is set one turn out on H/L and was adjusted a tad from there looking for an ideal idle. No dice though. Is there anything else I'm missing? When the saw last ran and idled correctly it had a little bit of a high idle but was not racing and was still 4 stroking at WOT.

 

[Duane(Pa)]

Try a new Bosch or NGK plug

 

[woodgrenade]

I haven't tried a new one, but I did put one in from a saw that I know was running well. (NGK).

 

[deereguy]

Plugged exhaust screen?

 

[pioneerguy600]

If all else mentioned fails to help your saw pull the muffler cover off and take a close look at the piston. If you see vertical streaking there is your problem. 80 - 90 % of that series saw that I look at has scored pistons, mostly from leaking seals.

 

[Stihldoc]

OK, you've thrown lots of parts at it and it still runs the same? What does that tell you? It tells me that you're wondering what to replace next. That, unfortunately, and expensively, is no way to repair a saw. Before you flag me for being obnoxious, try to see it from my point of view as a technician who also teaches, that you're taking the wrong approach to solving the problem. Let me first give you some advice about systematic troubleshooting, then make a suggestion. I repair Stihl saws all day long, each day, everyday. Every time I guess at a problem, I waste time. Stihl has an "engine check" sheet that, if followed, will lead you to the problem every single time. Do I use it on every job? No. Once or twice a a day? No. But, when all else fails, it is a great reference tool to help one remember to check the simple, stupid things that are so easily overlooked in unit diagnosis. Ask your dealer for a copy of it- hopefully they have one somewhere. Any dealer that doesn't isn't worth a crap. Now that I've beaten you up a little, let me congratulate you for trying to help your friend. The world needs more people who are wiling to try (and learn).
What sticks out of your post to me is the statement "the fuel hose and filter are not clogged". I see lots of 1123 series (025, etc) saws with cracked fuel hoses. This failure willl not nescessarily leak fuel out, but will always leak air IN. remove the hose & filter from the tank. Remove the filter and plug one end. Apply a vacuum pump to the other end and see if the hose leaks. This simple test will confirm the integrity of the hose, or not. Unless this saw has a damaged piston or cylinder, or an air leak, the problem is bound to be a simple one. Its always the simple ones we overlook that ultimately are the cause of the problem. The 025 is a good little saw. Figure it out and be proud of your systematic troubleshooting. Keep us informed.

 

[woodgrenade]

Thanks for the response guys. I'm not wet behind the ears remotely when it comes to saw repair, but this one has me scratching my head. Compression is 140. Exhaust and intake sides of piston look great.
I will vacuum test the fuel line tomorrow and see what I get.

 

[CTYank]

I'd check for loose bits like the cyl. & the intake tract, after you tell us about the spark-arrestor screen.

Then come the crank seals. Vac/press test.

 

[jughead500]

I would check the crank seals.have you pressure tested the crankcase?

 

[woodgrenade]

I checked fuel line. Both pressure and vac checked out fine. Next step is crank seal check. I'll try to block off muffler and carb with inner tube material. I would love to get my hands on Stihl block off plates.
The thing that gets me is that the saw was still 4 stroking perfect at wot. And would only high idle a tad before any hard starting hard idling problems started.

 

[woodgrenade]

I've been too busy to post, but it was the crank seals. PTO side was completely torn.

 

[Tothemax]

I have an 025 in my garage that is damn near doing the same thing. It will start fine but will not hold a consistent idle. New crank seals, impulse line, fuel line, etc.

I can get it idling good then the next time you start it, it is all over the map. Or sometimes I cannot get it to hold a consistent idle not matter what I do.

 

[woodgrenade]

What did you re seal the bottom end with? Do you think it held? Did you re vac check it?

 

[Tothemax]

I used high temp permatex

 

[woodgrenade]

That should be fine. Did you vac test it again?

 

[Tothemax]

I don't have a vac tester. Just a compression tester.

 

[Wood Doctor]

The Stihl 025 fascinates me. The cracked fuel line is a common problem that drives you bonkers. Usually the crack appears right near the carb intake area and is hard to see. Even a small crack will ruin the fuel mixture. I've fixed several this way.

Then again, I have an 025 with a mind of its own. Get this. It will start cold after a single choke and then two more pulls at fast idle and you think everything is great. Then it conks out on idle after a few revs. Try to restart it and it's a no-go--flooded. Let it sit 10 minutes in the sun and pull again on fast idle. It runs perfectly after that sun bath and it will run all day with no problems. It's as if it wants some vitamin D.

What says the Forum?

 

[Wood Doctor]

I suppose I should start a new thread on this, but my 025 went hunting for sunshine again today. It ran sluggishly for about two minutes and stopped on an idle. I waited ten minutes with the saw in the sun and started it again. The engine ran perfectly after that for the whole tank. It's using the sun as a wake-up call, but only after a short snooze following a cold start.

This saw has a personality all its own and may be addicted to vitamin D. Any suggestions on how to eliminate the addiction?

 

[old-cat]

vitamin d pills?

 

[Wood Doctor]

vitamin d pills?

Nice bump. I don't have the solution either. opcorn: