Help with my Stihl hedge trimmer

Viking Jeeper

Viking Jeeper

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I have a Stihl HS46 gas hedge trimmer. Currently it will only idle, when I try to accelerate the engine is just bogs down.

I have adjusted the carburetor high speed, low speed and idle speed settings according to the owners manual.

The machine is about 5 years old and has been well cared for and used less than 12 times a year.

I have inspected, cleaned and re-lubricated the gear box and it turns easily.

The air filter is original but the engine performance does not improve when I take the air filter off.

The spark plug appears to be in great condition.

Fuel: I only use ethanol free fuel in all my small engines. It is properly mixed in a 1 gallon can with Stihl synthetic oil (their highest grade). I recently put the proper amount of Seafoam in the fuel mixture to help with a performance issue with the blower and it seemed to help. The same fuel is in a blower, line trimmer and metal blade edger, all work perfect.

The trimmer was working normally then it started having issues running at proper RPM. The issues got worse quickly and within 10-15 minutes of use since the issue first came up it was unusable.

Any ideas of what is going on here? I have time and a teenage helper, I want to get my bushes trimmed! The engine will start and idle normally but any attempt to rev up the engine and get the blades moving results in a bogged down engine and no increase in RPM.
 
I have a Stihl chain saw and it was doing the exact same thing. I was running the Stilh no ethanol 2 stroke fuel. After an hour of trying to adjust it I decided to dump the fuel out of it and put some of the pump gas 2 cycle fuel I had mixed up for my weed eater and it ran perfect. A year later I tried the premix stuff again and had the same results. Could be worth a try it worked for me.
 
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Pull the spark arrestor screen off the exhaust. Either clean and replace or let the ol girl eat without it.

Page 19 (21 if you use the search box): https://www.stihlusa.com/WebContent.../STIHL-HS-46-56-Owners-Instruction-Manual.pdf
Wait for the engine to cool down completely before performing this work.
N Use a 15 mm socket wrench to unscrew the spark arresting screen.
N Clean the spark arresting screen. If the screen is damaged or heavily carbonized, fit a new one.
N Refit the spark arresting screen and tighten it down firmly.
 
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I had a chainsaw behaving the same way, my fix was to pull the fuel filter and hose out of the gas tank and clean the filter with compressed air.
If it would idle but not rev up that sounds like fuel delivery to me.
Of course now that you have played with the carburetor you my have to readjust it. In my experience modern 2 stroke carbs don't just slip out of adjustment.
 
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S.McArthur said:
Pull the spark arrestor screen off the exhaust. Either clean and replace or let the ol girl eat without it.
Click to expand...
It appears as it was the spark arrestor, runs fine without it. Thanks @S.McArthur ! Any issues with running without the spark arrestor? How to clean it?

tJNwgHy8SvKPQ74Q5pJoaA.jpg
 
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S.McArthur said:
Pull the spark arrestor screen off the exhaust. Either clean and replace or let the ol girl eat without it.

Page 19 (21 if you use the search box): https://www.stihlusa.com/WebContent.../STIHL-HS-46-56-Owners-Instruction-Manual.pdf
Wait for the engine to cool down completely before performing this work.
N Use a 15 mm socket wrench to unscrew the spark arresting screen.
N Clean the spark arresting screen. If the screen is damaged or heavily carbonized, fit a new one.
N Refit the spark arresting screen and tighten it down firmly.
Click to expand...
I was going to suggest the same thing. Clean the screen on the exhaust. I had a pole saw that did the same thing, and it fixed it.
 
I started using coleman fuel in my weed wacker out of desperation 2 years ago and since then it has yet failed to start so that's all I use now. I suspect it has to do with the regular gas additives and sitting so long between each use,
 
Mike the Silver TJ said:
It appears as it was the spark arrestor, runs fine without it. Thanks @S.McArthur ! Any issues with running without the spark arrestor? How to clean it?

View attachment 150897
Click to expand...
I take mine out of everything, it lll be a little louder. All it does is keep from anything coming out of the exhaust and starting a fire.
Just use any carb cleaner type cleaner and a brush. Nothing to it, it’s a 2-stroke, they smoke and gum up.
 
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