Stihl HS80 Hedge Trimmer won't start - black soot & moisture from exhaust

Discussion in 'Mechanic and Repair' started by Deferred Maintenance, Jul 23, 2019.

  1. Deferred Maintenance

    Deferred Maintenance LawnSite Member
    Male, from Miami
    Messages: 11

    Looking for some help on where to start repairs on my Stihl HS80. I can't get the engine to turn over. Using the normal start procedure, I pull and pull but it won't start. I noticed black soot and wetness from the exhaust under trimmer. I think some black smoke too.

    It's overdue for routine maintenance, so I'm going to order the filters & plug to replace. Any ideas what might be the root cause or where to start looking?
     
  2. Mumblingboutmowers

    Mumblingboutmowers LawnSite Senior Member
    Messages: 728

    It could be flooded for many reasons. Rather than guessing and throwing parts at it, take it to a small engine guy and to get a diagnosis and see if it's worth fixing. It's often cheaper to pay a professional to look at something and save yourself a ton of time and aggravation. And if I got my use out of a tool and it starts having issues, I go buy a new one and either sell or giveaway the other tool as-is.
     
    GrassManKzoo likes this.
  3. hort101

    hort101 LawnSite Fanatic
    Male, from S.E. New England
    Messages: 18,130

    Have you ever looked at the exhaust port and spark screen?
    Does it try to start?
    Ever changed the spark plug?
    How many hours on it?
     
  4. GrassManKzoo

    GrassManKzoo LawnSite Platinum Member
    Male, from Kalamazoo, MI
    Messages: 4,734

    Should probably stop deferring your maintenance Thumbs Up
     
    hort101 likes this.
  5. dishboy

    dishboy LawnSite Fanatic
    from zone 6
    Messages: 7,321

    Pull the plug and see if it is wet, if so spray with carb cleaner-compressed air , motor engine over with plug out to clear the cylinder and see if it will fire.
     
    Deferred Maintenance and hort101 like this.
  6. OP
    OP
    Deferred Maintenance

    Deferred Maintenance LawnSite Member
    Male, from Miami
    Messages: 11

    That sounds like a good place to start. Will work on that today and see what happens.
     
  7. BigFish

    BigFish LawnSite Fanatic
    Messages: 5,261

    If you gots air, blow into plug hole while cranking to help clear it.
    Leave the air filter off till ya get it running. Can also swish the air filter in a bit of gas and blow dry to clean it.
    I very rarely replace stihl air filters, jes clean em.
     
  8. OP
    OP
    Deferred Maintenance

    Deferred Maintenance LawnSite Member
    Male, from Miami
    Messages: 11

    Ok, update.

    1. Cleaned air filter. It wasn't too bad. I left it off.
    2. Spark plug was wet. Blew out with air.
    3. With choke off, no air filter, and throttle wide open, I cranked it 60 times. No start.
    4. Gas and black soot at the exhaust.
    5. Took off the spark arrestor assembly. Fuel and black soot came out. IMG_8076.JPG IMG_8074.JPG IMG_8071.JPG IMG_8068.JPG IMG_8067.JPG IMG_8066.JPG IMG_8065.JPG
     
  9. OP
    OP
    Deferred Maintenance

    Deferred Maintenance LawnSite Member
    Male, from Miami
    Messages: 11

    I cleaned out the spark arrestor screen thoroughly. Was going to put it all back together when I noticed some black buildup behind the spark plug. Is that carbon deposits on the cylinder? IMG_8082.JPG IMG_8081.JPG IMG_8079.JPG IMG_8077.JPG
     
    hort101 likes this.
  10. hort101

    hort101 LawnSite Fanatic
    Male, from S.E. New England
    Messages: 18,130

    Check the exhaust port behind where tje spark screen gos and clean any build up

    I originally jumped the gun it seems you might also have a flooding issue as others said
    If the carbs leaking fuel it will flood cylinderThumbs Up
     

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