OutdoorKing Repair Forum Forums Repairs and Maintenance Questions on Chainsaws and Concrete Cutters Petrol Chainsaws and Concrete Cutters Tough starting Stihls

Hi Fellas,
My Dad owns 2 stihls..one is around a year old (a 390?)& a new small 14inch baby.He has terrible trouble starting the big saw,but once it goes,it starts fine each time.
The new baby saw is 2 hours old & wouldn't fire the other day.We tried for 20 mins.

What's going on?Is it fuel quality,plug issues...???

My dad had an old 034 for years,so he's no novice. I think he's using a good fuel mix & always keeps the chains sharpened & saws clean.

Any thoughts??

Thanks,
Jim.

With the older saw, the first thing to suspect is the spark plug, because it has the right symptoms: hard to cold start, not so hard to restart. However if it had been standing a long time when it was hard to cold start, stale fuel in the carburetor is also a possible problem. Unless you deliberately run the carburetor dry before you store it, the petrol can dry up leaving oil, which won't go through the jet under venturi suction alone. So, you might try a simple service: clean or replace the air cleaner element, replace the spark plug if there is a possibility it has run 15 hours or more, run the saw dry of fuel, let it cool off for a couple of days, then see if it starts better. If not, you will need to do a full service, tuning the high and low speed mixture controls, and probably including overhauling the carburetor (replacing both diaphragms) if the saw is more than 5 years old.

Because the new saw had the hard starting characteristic immediately from new, it is more difficult - I had a little Sachs Dolmar saw that had the same problem, and I finally solved it by donating it to a local service club. I think all you can do is approach it from first principles: check the spark, then try priming it with a spoonful of fuel directly through the spark plug hole to see if it will fire when you do that. If it will fire when primed, but not otherwise, you will have to investigate the fuel system: tank venting, fuel lines clear and not split, etc, then tune the carburetor and possibly overhaul it. Chances are it is a defective component or adjustment: bad spark plug, split fuel suction hose, bad in-tank fuel pickup filter, stuck tank vent, kinked hose, foreign body or burr in the carburetor, etc. Start with the ignition then the fuel tank and work forward, leaving the carburetor for last: many people who "fix" hard starting chainsaws by attacking the carburetor make things a lot worse.

Some chainsaws require oddball starting techniques, and if you don't happen to find out what yours likes, life can be miserable.

Every Stihl I've owned (quite a few over the years!) the same cold starting process has worked (unless, as Grumpy mentioned, the saw has been sitting for a long time).
1. Throttle on start detent
2. Choke full on
3. Check ignition is on
4. Pull starter, anything up to 3 times, usually, and the engine will "burp"
5. Choke off
6. Pull starter again - engine runs - let it warm up for 20-30 seconds before letting it idle.
I have found the smaller saws in particular to be very sensitive to dirty air filters/old spark plugs.

I agree with Igor's starting procedure, with two possible variations. First some saws (including an old Partner R14 I used to like very much) have a half choke click-position. After the burp these saws will have to be restarted on half choke, then open it the rest of the way when you can (after about half a minute to one minute, for the R14). Second, some saws take quite a bit more than 20-30 seconds before they will idle - perhaps a minute or even two minutes.

And that tiny Sachs Dolmar, plus an awful locally-made Atom, were the only ones I've had that were just a pain in the backside, rather than needing a special technique. The Sachs had the redeeming virtue of singing a beautiful song at full throttle once it warmed up. The Atom had no redeeming features at all.

Thanks for the quick replies.
The larger saw works each week,& runs OK once started.It hasn't done much work since new.

The small,new saw was sparking OK the other day when we were trying to start her up.

I read elsewhere that some guys just set the choke ON,pull twice,then set choke OFF & see if she starts....
I wonder if we are flooding the saws upon first try & not noticing that first kick when she tries to start up.Never had this crap with the old 034!

On a side note,am I best to use stihl oil & a premium fuel for the mix?

I'll try those tips & see how we go.

Thanks again,
Jim

I have a rather deadly old stihl 08s, with the correct procedure it starts and runs very well, this involves, full choke (3-4 pulls) till it burps, then pull again holding the throttle open a little with no choke. After about a minute it is warmed up enough to use.

Its a brutal saw but we are no longer able to use it for firewood since it does not have a chainbrake, a requirement by the council for use in the forestry area here.

My mobilco echo saw is another champion I have the same issue again here with lack of chainbrake.

It is possible that opening the choke before it burps will prevent it becoming over-rich, but I don't think the normal procedure (waiting for the burp) would prevent it from starting unless it had a fault such as a bad spark plug. You can find out though: after the engine has been run, let it get completely cold, set full choke with ignition on and throttle set to the start position (that is, the detent), pull it three or at most four times, and if it doesn't burp, immediately remove the spark plug and see if it is wet. In the normal course of events, if the ignition system works and the spark plug is good, you can't get to a too-rich situation without passing through a more-or-less-right situation on the way there, and it should have burped at that point. If the plug is wet, you most likely have a spark problem.

With regard to fuel and oil, I suggest you use the octane level recommended by Stihl. Standard unleaded is 91 octane and super unleaded is 95 octane. So far as oil is concerned, use a brand-name 2-stroke oil, in the proportions recommended in the Stihl owner manual.

Thanks for the replies.
We have a lot of good info to work with now,so will try all suggestions & see what happens.

Jim