Stihl 4 mix problems

Discussion in 'Mechanic and Repair' started by A Leaf Above, Aug 1, 2010.

  1. A Leaf Above

    A Leaf Above LawnSite Member
    Messages: 223

    Hello to all ,

    Was wondering if anyone else seems to be having trouble with there stihl 4mix handhelds lately ...I have 3 peices that in the last 6 months just seem to wanna stall ...I use 93 octane fuel , full synthetic stihl oil ...Now my 2cycle has absolutely no problems at all , just the 4mix.....I just bought a 110 stick edger and it was perfect when i came back from the dealer not even 3 weeks later it just seems to wanna cut out if it idles ....Is there problems with the 4mix since they have puttin up to 10% ethanol in fuel ? If so , what do you guys use as an extra additive ?
  2. Roger

    Roger LawnSite Fanatic
    Messages: 5,943

    Age of the units? How much service? Valves adjusted at about 150 hours?

    The ethanol question is a good one. I had to replace a carb on a Stihl chain saw because the ethanol destroyed a seal. I'm unsure why the ethanol has not done damage to my other Stihl products. The chain saw gets little use, but the other Stihl handheld units (four of them) get constant use.
  3. stevetford

    stevetford LawnSite Member
    Messages: 10

    I can't offer any technical advice on the subject, but can tell you that you are not the only one. We have 2 FS90R's that are 2 years old now and to be honest have been totally abused. Used only 87 octane fuel and Valvoline 2 stroke oil mix 50-1 and to add to the abuse I work for the city that I live in and we get class D inmates from the city jail on work realease to do all the trimming and never had a problem with either weedeater. Trust me if these guy's can't break it then that really stands for something.
    At the first of this spring we bought a 3rd 90R new from the dealer. Been nothing but junk from day 1 and we actually wanted to give this one a better start in life. Bought plenty of the Stihl oil and ran only premium fuel. This trimmer has no power, very slow to accelerate and stalls all the time. Several trips back to the dealer have been no improvement. If we had not had such good results out of the other 2 trimmers then I would have never bought another one, so I don't know what the deal is. When we first took the trimmer back to the dealer his first question was what oil and what fuel we used. He was shocked when we told him, then mentioned how we treat the 2 older units and he said they should never lasted this long. As far as the ethanol, it is a good theroy but I doubt it is the culprit.
  4. The Lawn Ranger CT.

    The Lawn Ranger CT. LawnSite Member
    Messages: 194

    Bought a 90r weedwacker about 3 weeks ago and having the same problem, not only with a stalling but , after the first few times of use during the day it starts great, but each and everytime after that it wants to stall and then very hard to start, until the next day , and the cycle starts all over again~!
  5. lawnboy dan

    lawnboy dan LawnSite Gold Member
    Messages: 3,716

    the fix is simple -dont buy sthil 4 mix
  6. A Leaf Above

    A Leaf Above LawnSite Member
    Messages: 223

    WOW !! That is the most technical answer i have ever heard ..glad you can chime in with absolutely nothing to say ....Kinda too late for that isnt it ? geesh..
  7. A Leaf Above

    A Leaf Above LawnSite Member
    Messages: 223

    The 110 edger is under a month , the older 110 is 5 years old ..I have 4 br600s with no probs at all ..the 90 weed eater is about a year old i said all my 2 cycle is just fine ...just tryin to see if anyone else had any issues and how they resolved them ...I can always just up the idle a bit , but there is something going on ..all this stuff has only started in last 6-8 months ....before that all my 4mix stuff never had a problem for years with very little maint..i have tried Different gas stations also ..
  8. ricky86

    ricky86 LawnSite Silver Member
    Messages: 2,139

    Find another dealer.Find one with a Gold level mechanic. Way too much is blamed on ethanol. It is a convenient scapegoat for a lack of knowledge. One thing to check, remove the a/f, hold unit in it's normal operating position, then turn it on its side, carb down. See if fuel leaks out. If it does, it might be the tank vent leaking fuel into the a/f chamber. That will definitely cause stalling.
  9. unkownfl

    unkownfl LawnSite Gold Member
    Messages: 3,837

  10. A Leaf Above

    A Leaf Above LawnSite Member
    Messages: 223

    Thanks Unknown ...that is a good read ....Really appreciate the info .:cool2:

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