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Stihl BR420 won't start...HELP!

Discussion in 'General Industry Discussions' started by Gilmore.Landscaping, Aug 15, 2011.

  1. Gilmore.Landscaping

    Gilmore.Landscaping LawnSite Senior Member
    from Ontario
    Posts: 645

    So practically brand new br420 bought about 3 weeks ago but only used it about 4 times and hasn't been started in about 2 weeks and won't start.

    Any ideas? I put fresh gas....and yes its in the on position...also have been trying for a while so ti probably flooded by now but what should i try??

  2. sdm111

    sdm111 LawnSite Member
    Posts: 12

    Try a new spark plug if that dosen't work then the pilot jet in the carb. is probably clogged. With the ethanol fuels now they are real bad on carbs. If you have ethanol fuel in small engines I would reccommend starting them every few days or so. Fresh gas won't help if it can't get through the jets. Try a small spray of ether W/ lubricant on the air filter, if it sputters then you know it's the carb. ( by the way I don't condone the use of ether but a small shot will be o.k. ) P.S. hold the throttle wide open so it can suck the ether in.
  3. Swampy

    Swampy LawnSite Bronze Member
    Posts: 1,435

    Got that same issue with a older one, It fired and was running then puked out. Couldn't get it started again, changed out the spark plug (which is getting spark), changed out fuel filter, took the carb off and used carb cleaner. It still won't fire.
  4. sdm111

    sdm111 LawnSite Member
    Posts: 12

    With all due respect just spraying carb. cleaner is useless. The jets need to come out and be cleaned with a couple strands of fine wire twisted together, then sprayed along with all passages in the carb.
  5. Gilmore.Landscaping

    Gilmore.Landscaping LawnSite Senior Member
    from Ontario
    Posts: 645

    ok but why should the carb need cleaning already? its only has like max 2 hours on it?? And I have only used shell 91 with the stihl oil mix that came with the blower?
  6. ed2hess

    ed2hess LawnSite Fanatic
    Posts: 13,192

    This model floods very very easy and when it does you simply turn off the switch and pull the recoil about 20 times. Then turn it back on and try again without any choke. You only use the choke one time on intial start in the morning and thereafter simply pull cord. And during the day each time you go to start the unit releave pressure in tank by loosenign gas cap and tighten it back. This is the best machine stihl has ever made so don't give up on it.
  7. sdm111

    sdm111 LawnSite Member
    Posts: 12

    Always try a new plug first. In case it's too fouled out. It's not the run time that's good for it it's the down time that messes them up. With the fuel Ethanol is an organic additive added to fuel, when it sits up for a while it turns to a green slime. That coupled with the varnish that gas turns into dosen't take long to clog the tiny passages of a pilot jet. With small engines 2 and 4 stroke it can take as little as a week or so to clog it. New or old alike. All these engines need to run are spark fuel and compression if you have those it will run maybe not good but it will run. With a 2 stroke if you pulled and pulled consider the plug too fouled to run. Even cleaning the plug once it's glazed it's done. Stihls are great machines it's not the brand it's just what happens through design.
    Last edited: Aug 15, 2011
  8. tigerfan88

    tigerfan88 LawnSite Member
    from SC
    Posts: 82

    ed2hess is correct. it is flooded. i'm glad the rest of you cut grass instead of working as mechanics! never pull more than twice on choke with this unit.
  9. FLBR400

    FLBR400 LawnSite Member
    Posts: 2

    I agree that it's the best machine. I've got a BR400 that's 22yrs old. Never been a problem until recently. I've got spark, on 3 different plugs, even swapped out plug with my FS 66 that I knew was firing it. Got gas, but can't get it to fire. Have turned switch off, pulled 20 or so times, turned back on and nothing. Plug is wet, and is sparking, but can't get it to light. Any ideas?
    Last edited: Aug 19, 2011
  10. Gilmore.Landscaping

    Gilmore.Landscaping LawnSite Senior Member
    from Ontario
    Posts: 645

    Yep this nail it. Also apparently I am supposed to start it full throttle, which the other guy at the dealer told me to start it at idle, thus why it got flooded in the first place. Removed the spark plus and dried it off, as well as blowing out the cylinders a little. Works great again. Thanks

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