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New Guy- Dead Trimmer with Backfire

John_99_2007

LawnSite Member
Location
Houston, TX
Stihl trimmer quit today, then wouldn't start. No, fire..nothing. If I prime it and choke it I get a backfire, and a little smoke out the air filter. Anybody seen this before. Trying to grow my business and would like to keep this trimmer going.
 

KTO Enterprises

LawnSite Bronze Member
sounds like the flywheel keyway is stripped. Somehow it is not sparking when it needs to
 
OP
J

John_99_2007

LawnSite Member
Location
Houston, TX
Think I could look at it myself. I've never pulled apart a trimmer but have been inside other engines. Probably not worth the cost of getting a repair vs. buying another.
 

KTO Enterprises

LawnSite Bronze Member
With the price of new stihl equipment, most repairs are economical. Especially if you can repair yourself
 

topsites

LawnSite Fanatic
No offense but if you are new then you probably just flooded it.

Try this tomorrow:
Pull the plug and clean it (compressed air would be nice, but just air dry it).
If the plug is fouled (black), replace it. Likely you need a Bosch 7547 / WSR6F...
Should the Auto parts store be closer than the dealer, an Autolite XST2974DP is the equivalent.
Reinstall.

Then, if you suspect it could be flooded, this should clear the chambers:
Ignition ON - Choke OFF - Throttle LOW (no throttle).
And pull it in this fashion 4-5 times, if it fires fine but don't try to keep it going, just pull 4-5 times, then:

And the Stihl 2-clyde quip starting procedure:
Ignition ON - Choke ON - Throttle set for start (lock it in place).
Pull it ONE time.
It should be running, turn the choke off, takes practice but if you do it quickly it might stay running.
If not, just pull it again with the choke off and the locked throttle.

Notes: If it wants to run at any time just let it be, don't try and play with the throttle just yet, either it's locked on high or it's off and either way if it starts it should run, you need to give it 20-30 seconds of warm up then you should be able to get going.

Good luck.
 
If what Topsites mentioned doesn't work, remember that Stihl handtrimmers are notorious for ignition problems when subject to a hard shock.
If your dude dropped it on a hard surface, more than likely he broke the windings in the coil.
This would result in the unit running fine in the morning then not running at all later in the day.
At least this is what I have observed seven times in two years, anyways.
 
OP
J

John_99_2007

LawnSite Member
Location
Houston, TX
No offense at all. I'll take all the advice I can get. My first thought was that it was flooded, too. I waited a few hours, but mayby not enough. I'll try again tomorrow after checking the plug. Thanks for the starting sequence tips. Does the backfire mean anything or is this normal when these engines don't start? A few timesbefore it's taken 10 or 15 pulls to start, but I've never heard it backfire till today.
 

KTO Enterprises

LawnSite Bronze Member
The older mine gets, the more pulls it takes to fire that puppy up.
 

Wells

LawnSite Member
Location
SLC UT
Have you pulled the spark screen out of the muffler. Once they start to clog up it causes the machine to eventually stop running or it runs poorly, acts like it has no power.
 
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