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  1. #1
    Gold Member
    Join Date
    Sep 2008
    Posts
    483
    Location
    North East TX
    Tractor
    Ford 7710 II FWA, NH TB110 FWA w/ NH 46LB loader, JD 5303 2wd w/ loader

    Default Stihl SG 20 Backpack sprayer - unable to pressurize !!! NEED HELP

    I have a Stihl SG 20 backpack sprayer that I purchased last year. I used it all last year and this year up until now. I have been very careful to wash it out and de-pressurize after each use. I have also been conscious about oiling the pump piston. Yesterday I filled it up with water / roundup mix, strapped it on my back and set off to spray my yard perimeter. To my utter disgust, I could not pump up any pressure (very little) I pumped and pumped and pumped, but could not get pressure. I called my dealer and asked about common problems so I would know where to start but got no help. After some reading (interned and instruction manuel, I cleaned the filter in the hand wand (It did in fact need cleaning). Still unable to pressurize. Then I took the piston out of the pump and examined it (lots of oil, but no apparent problems). I then opened the chamber housing the ball bearing (no apparent problems). I cleaned meticulously and put her all back together (no improvement) The only thing I noticed is that there is lots of cracking in the hose where it bends. However, there are no leaks. Could it be possible that the cracks are allowing air to escape (and thus I cannot get pressure?) while not allowing water leaks ?? I tend to think no.

    Has anyone else experienced this problem? What would you suggest I try next? thanks.

  2. #2
    New Member
    Join Date
    Mar 2012
    Posts
    1
    Location
    Arlington, TX
    Tractor
    Stihil SG20, Ford 860, Ford 220

    Default Re: Stihl SG 20 Backpack sprayer - unable to pressurize !!! NEED HELP

    I have the exact same problem with my Stihil G20 sprayer. Did you ever find out what prevented your sprayer from building up pressure when pumping. I have also checked and cleaned everything, but the hand pump fails to build up any pressure. I have also tried changing the pump o-ring with no success.

  3. #3
    New Member
    Join Date
    Apr 2012
    Posts
    1
    Location
    missouri
    Tractor
    none

    Default Re: Stihl SG 20 Backpack sprayer - unable to pressurize !!! NEED HELP

    There are two check valves that may have deposits on them. For the first one unscrew the fitting where the hose comes from the tank to the bottom of the pump. When you remove the fitting you will find a steel ball clean it and the seat where it sits with steel wool and replace.
    If this does not fix the problem check the one on the side of the pump tube toward the bottom. There is a brass cap you can loosen with a cresent wrench and there you will find another steel ball and you will need to clean it as well. Hope this helps.

  4. #4
    New Member
    Join Date
    May 2013
    Posts
    1
    Location
    olympia,washington
    Tractor
    john deere 3220e

    Default Re: Stihl SG 20 Backpack sprayer - unable to pressurize !!! NEED HELP

    I just started experiencing the same problem. i purchased a new sg20 on may 1st, it sat in my shop until I attempted to use it yesterday. It would not pressurize the chamber at all. I took it back to the dealer. They gave me a new one and some BS about it being a fluke. Got it home and ran 1.5-2 gallons of spray through it and it quit again. I again ran it back to the dealer. According to them the o-rings that seal the pump pressure chamber are drying out which is causing from cracks which allows all the air to escape. I,m on my 3 rd one in 2 days and will try using it this am. Otherwise I will head to Wilco, or dells or the local farm store and by the $50.00 which has worked fine for the last 3 years.

  5. #5
    kmm
    kmm is offline
    New Member
    Join Date
    Jun 2013
    Posts
    1
    Location
    chesapeake beach, MD
    Tractor
    stihl hg-20

    Default Re: Stihl SG 20 Backpack sprayer - unable to pressurize !!! NEED HELP

    I removed the two check valves. Wiped the steel balls and inside with a paper towel. I then sprayed lubricating oil in the ball hole. put it back together and so far it works like new

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