Petrol Strimmer won't start

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HaplessHubby

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I have a Stihl FS38 petrol strimmer which was working well until I tried running it at less than full throttle for a few minutes. The engine stalled out and all efforts to restart it have failed.
I tried following manufacturers recommendations for starting a possibly flooded engine without success. I have tried draining the fuel cranking the engine several times to clear the carb, and refilling with fresh fuel. I have also replaced the spark plug. Still no joy.
Does anyone have any suggestions on what might be the problem preventing this unit starting?
 
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The motor may not actually be flooded so try choke for a couple of pulls.
Is the primer bulb full of fuel?
John :)
 
Thanks for your prompt response.
Still no go after using choke and yes the primer bulb is full.

Jim
 
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OK, the next thing to do is to see if there's actually a spark, Jim. Can you place the plug on the metal part of the engine, ignition switch on, and crank it over? (Sometimes the spark can only be seen in the dim light.)
This is a 2 mix engine, and a 50:1 fuel/ stihl oil mix is recommended.
John :)
 
Got spark plug tested as you suggested and it seems there is no spark visible. Have tried several ways to arrange this including testing with a conductivity meter to ensure electrical contact and there is definitely no spark.
 
OK, this means one of two things.
Try disconnecting the thin black wire that comes out of the igniter unit (black plastic box on the side of the flywheel with the plug lead coming out of it.) This disconnects the cut out switch on the handlebar.
If there still isn't any joy, then its the igniter unit itself that's at fault (approx £50.) Igniter faults do happen from time to time but please bear in mind the spark can be hard to see on occasion so often enough I try the thing in the dark!
Good luck with it
John :)
Sorry, I'll just edit this one......Stihl screws are TX (Torx) 27.
J.
 
Looks like I cannot access the igniter unit to disconnect any wires without removing the grey plastic housing on my FS38. Is there a specific way to do this as there appear to be several screws on the housing which may or may not be holding it in place and I don't want to remove any more screws than is necessary? Or is there a simpler and better way to access the igniter unit..?
Any advice welcomed
Jim
 
Disconnect the wires from the stop switch, doesnt eliminate which may shorted, coil or wire, but its a start for a rookie .After you have been pulling like mad to try and start it, have you taken the plug out to see if its wet?....if its dry, tip a teaspoon of fuel into the plug hole and see if it fires....or if you have any carb cleaner remove air filter and squirt some into the carb opening with the choke open.
litl
 
Last edited:
The stop switch is in the forward engine plastic, just back from the D handle.....personally I wouldn't recommend dismantling that far.....unfortunately the switch doesn't pop out of its housing either.
Anyway, you'll see that Stihl are masters at plastic design (once the thing is back together again :eek:) so take some of the screws out from the area surrounding the recoil starter until the covers come free. You may have to undo such parts like the fuel tank before this will happen though.
One good point.....if you get anything wrong, it just won't go back together properly.
If you manage to access the igniter you'll be able to turn the engine over fast enough (plug out, naturally) by spinning the flywheel by hand.
One tip.....if the screws are plastic to plastic they are a very coarse thread - if they are plastic to metal they are conventional.
Good luck if you get stuck in!
John :)
 
I use a very old timing light that connects in series with the spark plug to see if my strimmer / mower is sparking. I doubt you can buy anything that basic now but would one of those spark plug testers that fit on top of the spark plug do the trick? Same basic idea.
 
DaveHerns said:
I use a very old timing light that connects in series with the spark plug to see if my strimmer / mower is sparking. I doubt you can buy anything that basic now but would one of those spark plug testers that fit on top of the spark plug do the trick? Same basic idea.
Click to expand...
Thats my go to tool of choice for diagnostics, see if the engine is firing under compression or watch the the light on a misbehaving running engine to tell if its fuel or spark....and yes one of those jobbies that fit on the plug top will do the same job

litl
 
Sound ideas chaps - I prefer the services of a passing youth, persuaded to stick his finger in the plug cap :eek: The trouble with Stihl stuff is that the plug lead is so cut to size, even if you use a slightly longer plug it won't connect!
A tip of the trade (not that I'm the trade) is to pop the exhaust silencer off which gives you a good view into the cylinder.....any scoring indicates likely compression problems.
John :)
 
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