Difficulty starting Stihl chainsaw

[Dave and Verity]

It fires OK, but if you let the revs drop it fizzles out. Hot or cold. Any clues?

Dave

[Wendelspanswick]

If you look closely by the handle there are 3 holes, normally labeled H for high, L for low and T for tickover. You need to use a very thin flathead screwdriver in the T hole, turn it a small amount clockwise (just a few degrees at a time) to increase the tickover revs.
Best bet is to download the appropriate Stihl manual as chances are all 3 carburetor adjustments will be needed, or take it into a dealer to be tuned.
Where abouts are you?

[davetb]

It fires OK, but if you let the revs drop it fizzles out. Hot or cold. Any clues?

Dave

This is a common occurance for me.
I am not particularly mechanically minded.

My usual order of 'sorting' is
1. Give it a clean up, esp. Air filter, and check oil is getting to chain, and chain moves easily.
If no joy, then
2. New fresh fuel
The change of fuel normally sorts things, if not then
3. Change spark plug
This usually sorts out 95% of problems.

I think most of my issues are old fuel.

I then have to give it to someone who knows more about 2 stroke engines to sort out.

[SimonFisher]

2. New fresh fuel
The change of fuel normally sorts things, if not then
3. Change spark plug
This usually sorts out 95% of problems.
I think most of my issues are old fuel.

Is the spark plug changing needed because the old one has waxed up because of stale fuel?

If you keep having problems caused by fuel going stale, you might want to consider alkylate fuel - http://www.aspenfuel.co.uk/clean-facts/alkylate-petrol/

I use it in all my machinery engines (chainsaw, brushcutter, vac/blower, generator) and have no problems starting them regardless of how long they've been sitting unused.

[Dave and Verity]

Thanks for the answers, it was serviced about 5 hours cutting ago, so don't suspect filter, plug etc. Fuel is fresh. Have just fitted a fresh chain, but don't think this could have any effect. I'm in Coltishall, Norfolk.

Thanks all.

Dave

[SimonFisher]

... it was serviced about 5 hours cutting ago ...

Take it back to whoever serviced it?

[Terry]

Air filter needs regular cleaning - fine saw dust is flying around and getting sucked in all the time while cutting. I give mine a quick clean every time I fill up fuel and oil. It takes seconds and nothing builds up.

davetb - if having old fuel problems, definitely go with Simon's suggestion of Aspen alkylate fuel - it is more expensive, but you wont be throwing any away as it does not go off like petrol. Its also much better for your machines and most importantly much healthier for you.

[davetb]

davetb - if having old fuel problems, definitely go with Simon's suggestion of Aspen alkylate fuel - it is more expensive, but you wont be throwing any away as it does not go off like petrol. Its also much better for your machines and most importantly much healthier for you.

Hi Terry,
I went to the Royal Welsh Show today and found the Aspen display.
I have a dealer about 6 miles away so should probably try it.
I have 3 saws and rarely use 2, even my current favourite hasn't been started for a few months.
Cheers, for the advice.
Dave

[oldclaypaws]

I just stick in the recommended small addition of Briggs and Stratton fuel fit to every 5 litres, it has similar benefits as Aspen at a fraction of the cost, its literally pennies. I've had the same fuel in my mower, brushcutter or saw for months without use, and they all seem to start fine again.

http://www.briggsandstratton.com/eu/en/support/videos/maintenance-repairs/briggs-and-stratton-fuel-fit

[Terry]

I just stick in the recommended small addition of Briggs and Stratton fuel fit to every 5 litres, it has similar benefits as Aspen at a fraction of the cost, its literally pennies. I've had the same fuel in my mower, brushcutter or saw for months without use, and they all seem to start fine again.

http://www.briggsandstratton.com/eu/en/support/videos/maintenance-repairs/briggs-and-stratton-fuel-fit

It might well have the same benefits as far as starting, but the longer term deterioration on certain plastics in the fuel system etc, not to mention the gumming up of carbs, will still be there and more importantly it does not get rid of the benzine and all the other harmful bits in petrol that we end up breathing in for hours on end. After a day of using machines on Aspen, you dont end up with the headaches and generally feeling unwell as you do with petrol.
I believe that in some countries (scandinavia, Germany) you may not use petrol in 2-stroke machinery anymore because of the health implications, but would need to confirm this. There is certainly pressure around Europe for this to become universal.