Can you diagnose my Stihl by listening to it?

[aboekman]

Stihl 026. It starts and idles well. But when I hold down the trigger wide open it just intermittently revs but wont sustain a high RPM. I replaced the fuel filter and line, air filter, spark plug, and carburetor and it still behaves the same. I adjusted the tuning screws appropriately...still the same. What's next?

 

[Ozhoo]

Try it without the air filter to confirm that pesky choke flap, after that check the impulse hose.

 

[user 122190]

I would start in fixing the little obvious things, and in doing so you might happen on "the" problem. That dangling and swinging felling dog needs tightening.

Me: I start taking it apart and cleaning everything. In doing so, you touch and see everything and find the problem that way, usually. YMMV.

 

[Kensie1988]

that to me sounds like intermittent fire on the coil a way to check is to pull it pull out the spark plug and see if the spark is jumping around instead of arcing smoothly across

Sent from my E6910 using Tapatalk

 

[user 122190]

that to me sounds like intermittent fire on the coil a way to check is to pull it pull out the spark plug and see if the spark is jumping around instead of arcing smoothly across

Sent from my E6910 using Tapatalk

Thats a new one.

 

[Kensie1988]

Thats a new one.

Happened on the last saw I built, when I pulled the plug it was like the spark was dancing around on the post and was orange and wasn't a single blue arc.

Sent from my E6910 using Tapatalk

 

[frank_]

arcing killswitch , loose wire maybe ?

 

[dmb2613]

Does it run better choked?

 

[aboekman]

Thanks everyone. I'll tighten everything up and try your suggestions. I do know the impulse hose is inserted properly as I just replaced the carb.

 

[PV Hiker]

Trace back both wires from kill switch for shorts. Bad coil, bad sparkplug boot. Take the pull starter cover off and check coil pickup for oil or dirt, oil film will ground out coil. Check air gap at magnet/ coil.

 

[HarleyT]

Try richening both carb screws 1/4 turn, see what happens.
Worry about dialing it in later, just try this.

 

[Mad Professor]

Try taking off air filter and see if the problem is still there. That will eliminate or tell that it's the choke flap. Warm it up first or it will be a PITA to start cold W/O choke.

From there check wires to kill switch/coil, and spark plug wire. Look for missing insulation. As PA mentioned debris around coil, besides at pickup around the grounding terminal.

Some spark plugs have a screw on terminal for coil wire, make sure that is tight.

Was problem there before replacing parts mentioned?

 

[huskihl]

It sounds too sharp to me to be fuel related. I’m going with electrical. There is a metal AV mount On the upper left that the coil and ignition wires rub on. I’d look there

 

[Ax-man]

I'm going to vote with the electrical guys . Sounds like ignition short.

 

[aboekman]

Try richening both carb screws 1/4 turn, see what happens.
Worry about dialing it in later, just try this.

Is richening left or right?

 

[HarleyT]

To the left.

 

[aboekman]

Try taking off air filter and see if the problem is still there. That will eliminate or tell that it's the choke flap. Warm it up first or it will be a PITA to start cold W/O choke.

From there check wires to kill switch/coil, and spark plug wire. Look for missing insulation. As PA mentioned debris around coil, besides at pickup around the grounding terminal.

Some spark plugs have a screw on terminal for coil wire, make sure that is tight.

Was problem there before replacing parts mentioned?

Thanks. I'll try this stuff tomorrow. Yeah, the problem prompted me to replace everything. The only benefit I saw from all the replacements is that it starts and idles a lot nicer.

 

[HarleyT]

See if it runs any better at all.

 

[HarleyT]

If it does run better, come back here for help dialing it in.
A wrongly adjusted saw can damage the piston.

 

[alexcagle]

Fire it up in the dark and see if you see spark jumping from a punctured plug boot, or somewhere next to the crankcase.
I had a cutoff saw doing that once.
The guy took his plug boot off with pliers a bit too aggressively.