What's to blame?

Discussion in 'Lawn Mowing' started by Richard Martin, Dec 3, 2004.

  1. Richard Martin

    Richard Martin LawnSite Fanatic
    Posts: 14,700

    I have been using Amsoil 100 to 1 synthetic 2 stroke mix for 4 or so years now. I have been mixing it with any name brand 87 octane fuel such as Exxon, Sunoco and Citgo. I have never, ever had a problem until yesterday.

    I was happily earning money when all of a sudden my Stihl BR420C looses a little RPM and then goes right back up. About 10 minutes later it does it again only this time it lost RPM for about 5 seconds. With-in about 20 minutes the blower won't hardly even run. After 30 minutes it just quits.

    I disgustedly take the blower back to my shop and check for water. Nothing. I checked the fuel tank breather and it's in good shape. Replaced the fuel filter and still the blower runs like it running out of gas.

    I pulled the carb off, took it apart, sprayed it down with some carb cleaner and put it back together. It still won't run right.

    So I went to the local Citgo, bought some fresh gasoline, mixed my Amsoil in it, dumped the old fuel out of the blower and filled it with the new mix. No change.

    I called my buddy and arranged to try some of his fuel. He uses 89 octane Citgo with Shindaiwa 2 stroke oil.

    We put the fuel in and it runs like a champ. No spits, sputters or hesitation.

    Now bear in mind that our state mandates a switch from oxygenated fuel to super oxygenated fuel in the winter months.

    Do you think the problem is with the fuel or the Amsoil? Or could it be a problem of the Amsoil not wanting to mix properly with the fuel or contaminating it somehow?

    Any ideas?
  2. dishboy

    dishboy LawnSite Platinum Member
    from zone 6
    Posts: 4,234

    Sounds like you got some water in the mix somewhere? When you got fresh gas was it with a fresh container wih Zero old gas?
  3. grass_cuttin_fool

    grass_cuttin_fool LawnSite Gold Member
    Posts: 3,503

    I kind of think its the fuel and oil combo. I am not a fan of the 100:1 mix but if it has been working for you for years i see no reason it shouldnt now. I dont know if I am dreaming this or if I read this somewhere that some oils and fuels dont mix properly
  4. olderthandirt

    olderthandirt LawnSite Platinum Member
    from here
    Posts: 4,900

    I would send a sample of the mix in and have it tested. If it turns out its the oil you may have damaged the blower with out know it at this point and amsoil would cover the cost of the repair / replacement if its the fault of the oil.

  5. out4now

    out4now LawnSite Bronze Member
    from AZ
    Posts: 1,796

    Had that problem with the Echo's before. Turned out to just be contaminated from one of the safety cans. It had rust particles in it and water and once carb was cleaned and rebuilt and fresh fuel was put in they worked fine. Threw the gas can into the pile of HAZ - MAT stuff that got picked up periodically.
  6. Richard Martin

    Richard Martin LawnSite Fanatic
    Posts: 14,700

    The gas was fresh with a completely empty can. The gas even came from 2 different stations both of which are Citgos.

    I have spoken to my neighbor since my original posting and he was having the same problem with his Echo blower/Citgo 87/Amsoil combo. He dumped that mix and put in the 89/Shindy mix and now his blower runs fine.

    I'm thinking that they're screwing up the gas so bad for winter that it won't even burn in these small engines.
  7. YardPro

    YardPro LawnSite Gold Member
    Posts: 3,563

    small engines actually don't require the quality of fuel that the new cars do.
  8. mtdman

    mtdman LawnSite Gold Member
    Posts: 3,137

    This is why I use the stihl oil in all my mix gas.
  9. dvmcmrhp52

    dvmcmrhp52 LawnSite Platinum Member
    from Pa.
    Posts: 4,205

    we are having the same problem with a 420 as you have explained.
    checked the filter, took off the spark arrestor, removed the muffler to check for carbon,etc. etc.
    Funny thing is when you refill the tank it runs well for a while.........
    I'm scratching my head for now as well.........
  10. Envy Lawn Service

    Envy Lawn Service LawnSite Fanatic
    Posts: 11,062

    Re-plumb it!!! Your fuel lines and/or rubber gromets have gone bad.
    They are old and today's fuel does aweful things to them.

    Trust me, replace them even if they appear brand new.
    I had the same thing happen to my stihl trimmer and echo blower right around the same time.

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