FS 200 saga

[pycoed]

Last year I posted about problems with a Stihl FS200 brushcutter my son had bought, well the problem is back! To recap:

 

Compression is good & piston /bore are unmarked.

Carb is new

Plug is new & works in another strimmer.

Fuel is new

Air filter is new

Fuel lines & filter are all clear.

Kill switch & wire are fine for continuity.

 

Last year there were problems with a weak spark, so I eventually fitted a new coil inc plug lead.

 

Bl**dy thing still won't start, so I pulled the flywheel to make sure it hadn't slipped on the key: all was OK. Refitted flywheel & refitted the new coil with a gap of 15thou via the flywheel magnet & the coil stator. Flywheel magnet feels fairly strong.

When pulled over with the plug out, the spark is pathetic - a weak white twinkle, compared to the shower of blue sparks I get from my aged strimmers (Echo & Danarm one of which is 34 years old! ). Spark is barely visible in direct sunshine whereas the older machines show perfectly clear blue sparks. I've tried plug gaps from 5 thou to 50 thou all with the same result.

 

Short of trying another flywheel (suggestions for finding one are welcome) - what else can cause a very weak spark - is it worth trying another new coil 'cos I can't think of anything else. Suggestions welcome because I am very close to doing a Basil Fawlty with this:001_rolleyes:

[wisecobandit]

Take off the single wire that goes to the coil, and then pull it over and see what the spark is like then, if it improves theres an issue in the wiring back to the kill switch. If not your issue is likely to be the coil itself.

I set the gap up with the card off a packet of rizzla papers.

[pycoed]

I've tried it with the kill wire disconnected from the terminal on the coil & it's just the same whether connected or not. Tonight ( first signs of madness) I even tried it with the original coil back on & guess what? Just the same!

[Stubby]

Could it be some thing making the coils break down after time . The first one and now this one ?

[Macpherson]

can you smell fuel in the cylinder after pulling it over lots? big fat blue sparks in sunshine can`t always be expected,....imo, cheers

[pycoed]

No play today on the FS200 - I had to do some emergency fencing & it was bloody hot to be digging in sections of telegraph poles! Brian the Highland bull had broken into hayfield, via a 6 ft ditch full of water & broken a "normal stockfence".

 

Any road up - there's plenty of fuel smell in the cylinder after pulling over - this episode, the spark is too weak even to fire Easystart , so I think another coil is the only thing left. I've already tried setting the air gap as small as possible to no avail, it is currently set at about 15 thou - the thickness of a business card.

[dig-dug-dan]

Ignition module?

[pycoed]

Well I've ordered another coil so I'll see what happens...

[pycoed]

Success! New coil fitted & away she went. Just cut for about an hour with it & all is OK. Let's hope this coil lasts better than the last one. Last one probably only worked for an hour of actual cutting, but y the time I had retrieved it from my son & got around to looking at it was probably 8 months, so no hope of a refund. The new coil (OEM but not genuine apparently)seems to be exactly the same as the defective one - the only markings I can make on on them are a faint "FL" embossed in the plastic jacket.

Anyway - he's living up near Bicester now, so if it goes on him again he can fix it himself!