Stihl hedgetrimmer mystery

[stevesjc]

Hi ,
So I have an hs 45 for a few years and its been generally ok with not much in the way of problems .
However recently it just dies mid way thru some light work .
My multimeter indicated the coil was gone so ordered a new one plus plug .
Fitted both and still no spark . have returned the coil as defective and got one elswhere and still no spark ..
Plug is fine in my chainsaw .
Have also replaced the switch to be sure and the kill wire works as it should according to my multi meter .
Its quite a mystery so any ideas welcome ?

 

[buzz sawyer]

Were the new coil and plug OEM? Have you pulled the muffler yet to check piston for damage? Checked the fuel filter and fuel line?

 

[SCMtnHaul]

I'm not sure if I understand you 100%--do you still have no spark after trying 2 new coils? Or do you have spark but now the trimmer suddenly shuts off while in use? If the latter is your situation you might check to make sure the fuel tank vent is functional. If you still have no spark then perhaps the gap between coil and flywheel is incorrect?

 

[J D]

How are you confirming spark/ no spark?
Have you set the coil gap correctly?

 

[stihltech]

Take a breath and start over.
Test spark with a large gapped sparkplug. Make sure it is well grounded to metal. I will use a jumper wire to the cylinder to be sure.
Remove the switch wire from the coil and test. This eliminates the switch circuit.
Also check that the coil is grounded to the cylinder. Have had some with this issue also.
Last but not least, does the flywheel have magnetism?
Flywheel key broken? Would not start but still have spark.

 

[stevesjc]

How are you confirming spark/ no spark?
Have you set the coil gap correctly?

Hi , when I do visual check in a darkened shed there is no spark .
For the coil gap so far just a business card to set the gap .

 

[Oletrapper]

Hi , when I do visual check in a darkened shed there is no spark .
For the coil gap so far just a business card to set the gap .

As Stihltech said, disconnect the kill switch wire from the COIL and then check for spark. jmho OT

 

[stevesjc]

As Stihltech said, disconnect the kill switch wire from the COIL and then check for spark. jmho OT

zilch .. I am gonna take the coil back next week and get another one .

Its not OEM as its too expensive here to buy stihl but an aftermarket version compatible with my machine and many others .

 

[stevesjc]

So an update on this .
I left it for summer as had lots on and just getting organised for autumn decided I would sell it for parts .
Then at the last minute noticed I had a broken down stihl fs 55 in my barn which I kept for spares , realising the two machines share the same coil I decided to have 1 last roll of the dice and swapped out the coils .
Fresh fuel and a a few pulls later and she runs !
Wont idle but I can come back to that and try to adjust it or even get a new carb .

I feel I have been very unlucky to have two non functioning / incompatible new coils and two different repair shops tell me its not repairable and i should get a new machine !