stihl br400 wont start.

Discussion in 'Mechanic and Repair' started by sure cut, May 24, 2008.

  1. sure cut

    sure cut LawnSite Member
    Posts: 28

    hi, i have just brought a stihl br400 backpack blower off ebay, it was advertised as "spares or repair" becase the guy said it will not start! i brought it as it was dirt cheap and just down the road from me.....anyway, i got it home and fired it over a few times, after 6 or 7 goes to my delight it fired into life, i only let it run for a minuit or so because i had taken the air filter off and the pipes wernt connected, after switching it off i have not been able to start it again, i have tried everything and am really stuck now, i have taken the spark plug out and found it was wet with petrol after i had been trying to start it loads, left it for a while with the plug out, cleaned the plug with a wire brush, and still no joy,
    there is definatly a spark from the plug and there is definatly fuel going to the bore as when sprking the plug by the hole the fuel ignites and get a little burst of flames out the hole.
    there is definate compression there when holding finger over spark plug hole (dont know what compression as i dont have a tester, but like i say it did run once, and sounded fine when it did)

    i dont know what else to try i am really stumped especially aftrer it ran the once for me but not again since.

  2. sure cut

    sure cut LawnSite Member
    Posts: 28

    just to add, i had tried fiddling with the h / l screws, but made no differance and wasnt sure where they were set, so i have set them to 3/4 turn out on H and 1 1/4 turn out on L i had also left the plug out for a while to evaporate any flooding, i THINK it almost fired a bit once but thats it. but i noticed after pulling it over alot i am sure there is some petrol on the head around the plug????
  3. jkilov

    jkilov LawnSite Bronze Member
    from MS
    Posts: 1,415

    There is a reason why it was sold for spares.

    Take it to someone to have the compression checked, it could be just worn out.
  4. sure cut

    sure cut LawnSite Member
    Posts: 28

    will do when i get the chance, i had it running again this morning, ran for a min or 2 then died, and again wont start now?!? i have removed the exhaust and it appears to have a clear exhaust port, although not exactly sure what i am looking for, but there is cqarbon build up around the edges but nothing major, looking for something i have read about, spark arrestor system in the exhaust??? what is this and how do i check, the exhaust is a seald unit,
  5. sure cut

    sure cut LawnSite Member
    Posts: 28

    ok, i now seem to have it running, found the spark plug lead was broke and bodged back together, i have tied it together a bit better and it seems to run now, will solder it in the morning. my next question is... i have been fiddling around with the H and L screws on the carb and now they are all unset, whilst running i had to adjust them to keep it running, the L screw is almost screwed right in and the H about 1 turn out, this doesnt seem right so how do you set them an the idle screw to start off with, and then fine tune?

  6. sure cut

    sure cut LawnSite Member
    Posts: 28

    anyone? thanks for the influx of replys :lol
  7. mountainlake

    mountainlake LawnSite Member
    Posts: 33

    You might want to take the carb apart and give it a good cleanig, needle valve might be leaking causing flooding. The low needle usually end up around 1 turn out not screwed in all the way making me think the needle might be letting in excess fuel. Unless it has limiter caps which don't allow much adjustment. Steve

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