How old is "old" gas

Discussion in 'Lawn Mowing' started by mtpisgah, Dec 4, 2006.

  1. mtpisgah

    mtpisgah LawnSite Member
    Posts: 11

    This is an update/question I posted concerning a BR550 in the thread titled "Stihl BR550?"

    I just bought a BR550 and used it for the first time Saturday. I put gas in it and it started great and ran for an hour or so before cutting out. I figured it was low on gas so I filled it from the same tank. It would start fine and idle fine in the middle choke position but as soon as I throttled it, it would die immediately.

    Gamba and Martin suggested I just take it to the dealer so I did. They said it was old gas (they said they tested it). The gas was only about 2 weeks old and my MS250 chainsaw runs just fine with it. Are the new 4-Mix engines just that finicky? I usually fill my car when I fill my gas cans and my car takes 93 octane so that is what my lawn equipement usually gets. I used Husqavarna oil in the gas and it has a stabilizer in it. Should I switch to the Stihl oil? Extra stabilizer? I just don't understand how it can idle so strong and die when I pull the throttle.
     
  2. WJW Lawn

    WJW Lawn LawnSite Bronze Member
    Posts: 1,330

    That makes no sense. Its not old after 2 weeks! Either your dealer was full of it...or it was old coming out of the pump...which would make even less sense lol
     
  3. Total.Lawn.Care

    Total.Lawn.Care LawnSite Senior Member
    Posts: 841

    I had the same issue with a FS90 4-Mix trimmer. I noticed that the primer bulb was not priming correctly and it was causing it to be hard to start and once started, it would cut it when I tried to throttle up. Took it to the dealer (2 days old) they said it was a problem with the carb, they installed a new one under warranty and I have not had another problem.
     
  4. saw man

    saw man LawnSite Bronze Member
    from utah
    Posts: 1,021

    Gas starts to varnish after 2 weeks. You shouldnt have problems with it after that time unless the station had a bad batch.

    Did they get it running? The oil mix you are using is fine and no extra stabil is needed unless you plan on having it for a longer period of time.

    Possible that it just needed the low and high adjusted on the carb.
     
  5. GravelyGuy

    GravelyGuy LawnSite Silver Member
    from Indiana
    Posts: 2,518

    If it revs up slightly and then dies, lean out the low end needle(clockwise).
    If it just bogs down and dies, richen it up(counterclockwise).

    This is assuming the top end is set for performance. You should not have to do this on a new one though. Take it back to the dealer and have them screw with it until it is 100% fixed. Don't let them jack you around on a brand new piece of equipment.
     
  6. jbell113

    jbell113 LawnSite Senior Member
    Posts: 654


    I seriously have a hard time believing this varnish thing. You can smell varnished gas but not after 2 weeks. I have started engines after they have sat for months and they ran fine.... although I dont make a habit of this. Now I may be wrong but I would like to get some other opinions on this
     
  7. pugs

    pugs LawnSite Gold Member
    Posts: 3,022

    I would like to know how they tested it. I am unaware of any tests for old gas. Other than looking at it and smelling it. Sounds like some BS to me.
     
  8. ed2150

    ed2150 LawnSite Member
    Posts: 174

    The dramatic temperature changes between night and day this time of year can cause small amounts of water to condense inside partially full gas cans, and it will cause symptoms like you're having.

    My RedMax blower starts to "stutter" at high rpm when my gas collects moisture (it doesn't take long with these temperature changes); a little Seafoam gas treatment or something similar straightens it right out.
     
  9. walker/redmax

    walker/redmax LawnSite Senior Member
    Posts: 367

    Wow, I usually begin the season with last seasons left over gas (3 moths or so). Never had any problems. Sounds like your dealer misdiagnosed the situation.:drinkup:
     
  10. MuleCutter

    MuleCutter LawnSite Member
    Posts: 212

    nah... gas should NOT varnish after 2 weeks. 2 months maybe but not two weeks. then gas will still be "ok" to use after about 2 months but i dont recommend waiting too much longer. and if you're using 93 octane... great. higher the octane the better. sounds to me that you just got a lemon carburator on that blower. also... check your gas for water just to be on the safe side.
     

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