Stihl FS 90 AV Electronic Brushcutter... worth repairing?

Discussion in 'Homeowner Assistance Forum' started by leejp, May 11, 2007.

  1. leejp

    leejp LawnSite Member
    Messages: 129

    I just came in possession of an older Stihl string trimmer. The bezel over the pull start says it's a FS 90 AV Electronic. Presently, it fires but does not start. The previous owner mentioned that it ran well until it was put into storage a couple of years ago and a carb rebuild kit is probably all it needs.

    The unit is literally built like a tank... In many ways better than the new Stihl models. It's practically all steel and with very little plastic. Cosmetically it looks excellent for what's most likely a ~20 year old machine (I suspect that it saw no commercial use). Even the warning labels on the shaft are still clearly legible.

    I need to get the engine going and I want to replace what looks like an early model polycut head with a string head. That would also require a new deflector with a cutting blade on it, correct?

    If I can still get parts for it and get it running I'll ditch my Ryobi but I'm wondering if it's worth the effort and the $$$ to get it operational. Am I nuts?
  2. cgaengineer

    cgaengineer LawnSite Fanatic
    Messages: 15,778

    If it ran the last time it was put up its likely to be the carburetor. The rubber pumps on the carbs get stretched out and refuse to pump. This carb is likely a Walboro style carb and is easy to repair. I would see if I could get the kit and repair really is an easy fix.

    It could be possible that the crank seals are bad which would cause it to suck air and be hard to start, but from how you are describing the engines/weed trimmers condition I would say its not the case.
  3. leejp

    leejp LawnSite Member
    Messages: 129

    With starting fluid sprayed into the carb I can get it to start and run a few seconds but it doesn't hold idle well and dies as soon as I open up the throttle. I think I'll buy a kit off of fleabay (~$10) and rebuild a carb.

    Like I said... I love the way this thing is built and since it was pre-emission laws it should run well with little/no maintenance afterwards (my take is that EVERYONE... Echo, Stihl... had a few bad efforts shortly after the emissions requirements kicked in. They all seem to have figured it out now though).

    Also... If I want to sue an auto or bump feed string head, do I need a grass deflector with a cutter blade mounted on it? I recall that years ago I had a redmax that had an auto feed that didn't require a blade.
  4. cgaengineer

    cgaengineer LawnSite Fanatic
    Messages: 15,778

    You will need to have line cutting blade on the Stihl...mine has one...if you dont have one it may be a bit aggravating when the line comes out and is too long.

    You can also go to a dealer and get the kit...about same price and most will have them in stock.
  5. laguna_b

    laguna_b LawnSite Member
    Messages: 1

    I have had my FS-90 for less than a year and when it failed to run properly, would die when accelerating, I took it in for warranty repairs. They claim now that the unit's carburetor needs replacing due to bad gas. They claim that bad gas voids the warranty and the carburetor can't be fixed. That sounds strange to me. Any ideas? They want $170 to repair it!

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