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FS94r fuel lines

Discussion in 'Hand Held Equipment and Tools' started by Cannon51, Mar 10, 2018.

  1. Cannon51

    Cannon51 ArboristSite Operative

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    My BIL brought his nearly new Stihl FS94r trimmer to see if I could get it running. He had taken the carburetor apart so I'm wondering if the fuel lines are on correctly. I got it to run for a few seconds but after it died it is dripping gas out the air filter housing. The only time I ever had this happen was when I had reversed the lines on the primer bulb. I took the filter line out of the tank and removed the filter, I put the line in a cap full of gas and pumped the primer. No gas was pulled through the line. I removed the black line at the end of the screwdriver from the carb and put it in the gas. When I pumped the bulb it did pull gas out of the cap. Is the bulb plumbed correctly? The line from the gas filter is connected on the other side of the carb, Should the gas be pulled through the carb, to the bulb and returned to the tank through the green line? I can't find much on the web about this trimmer.
    Cannon IMG_20180310_102406430.jpg
     
  2. DND 9000

    DND 9000 ArboristSite Operative

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    The fuel is drawn through the carburetor. It comes through the black line on the bottom of the tank and attaches the carburetor on the other side. (Not visible on your pic.) Then it goes the black line (where your screw driver is) up to the primer bulb and the green line is the fuel return line to the tank. I think your hoses should be hooked up correctly.
     
  3. Cannon51

    Cannon51 ArboristSite Operative

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    Thanks DND 9000. I guess either me or my BIL have something messed up in the carb. I guess I need to decide between a $10 carb kit, a $15 China/Ebay carb or a new Stihl carb. Appreciate the help.
    Cannon
     
  4. Cope1024

    Cope1024 Stihl Crazy

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    I had good luck with an eBay Chinese carb for my 025.
     
  5. DND 9000

    DND 9000 ArboristSite Operative

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    I don`t know if you are able to find an aftermarket carb for this. The original carb on that FS 94 is a Zama RC2-S243 rotary valve carburetor. The set of gaskets and diaphragms for that is part number 4149 007 1700 from Stihl.
     
  6. Cannon51

    Cannon51 ArboristSite Operative

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    Cope1024 likes this.
  7. Cope1024

    Cope1024 Stihl Crazy

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    That's a no-brainer, a carb kit would cost close to that.
     
  8. Cannon51

    Cannon51 ArboristSite Operative

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    I ordered the ebay carb this morning. ETA March 20. I'll report back after I get it. Thanks
    Cannon
     
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  9. sawfun

    sawfun Addicted to ArboristSite

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    Zama carbs are Chinese so giving the cheap EBay carb a chance only makes sense.
     
    Cope1024 likes this.
  10. Cannon51

    Cannon51 ArboristSite Operative

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    Looks like a "Mission fail" on me fixing the trimmer with the Chinese carb. I put the carb on this morning and it still would not prime through the bulb. I pulled the filter out of the tank, removed it, stuck the open line down in the tank and it would prime through the bulb. I had a new filter (not Stihl) that I put in it. It cranked right up but will only run up to about 3/4 throttle. I opened up the only jet on it 1/2 turn but that made no difference. I couldn't believe the filter was clogged, this thing is about 2 years old and he has always used Stihl oil. I tried the old carb after changing the filter but it still wouldn't run on it. I think it's time for him to take it to somebody that knows what their doing. I appreciate the help.
    Cannon
     
  11. tpence2177

    tpence2177 ArboristSite Operative

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    Fuel ran out of my fs90 carb when the metering level was wrong. It needed a full rebuild but ended up putting a stihl carb on it and it runs just fine now. Anyway you could pull up some close shots of them to make sure you have the fuel lines hooked up right?

    edit: sounds like ethanol is a problem if it’s already needing a rebuilt carb after 2 years so that’s probably why the filter was clogged too.


    Sent from my iPhone using Tapatalk Pro
     
  12. John Lyngdal

    John Lyngdal ArboristSite Operative

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    I opted for a Chinese carb for FS250 repair I just completed and it worked like a champ afterwards, so I think your problem is likely something else.
    The ribbed green hose on the FS250 is the fuel intake line (with the tank filter) that goes to the carburetor, something similar should be on your FS94.
    The short extension/fuel line connection on the priming bulb goes to the carburetor and the long extension/fuel line connection is the return line back to the tank.
    Sounds like you have a fuel starvation issue, to which there can be many causes. I would look at the filtered fuel line going to carburetor and see if there are any cracks or leaks that you can spot.
    Another thing that has bit me in the past was to not fully insert the filtered fuel line the entire length on the brass inlet tube on the carburetor. This resulted in a fuel restriction caused by a sharp bend in the fuel line.
    Hope this helps.
     
  13. Cannon51

    Cannon51 ArboristSite Operative

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    I found a Workshop manual for this trimmer this morning. https://www.************/threads/stihl-fs94r-workshop-technical-manual.465163/ I confirmed that the lines are routed correctly. I talked with my BIL yesterday. He said he blew into the fuel line going to the filter and something popped, I think I'll examine the line in the tank for a hole, kink or deterioration before I give up on it. I remember when I was changing the fuel filter the line inside the tank felt soft and mushy, wonder if it could be collapsing.
    Cannon
     
  14. TuckerSailor

    TuckerSailor ArboristSite Lurker

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    How did it go with the fuel line check.
     
  15. Cannon51

    Cannon51 ArboristSite Operative

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    I took the line out of the tank yesterday. I couldn't find any holes or blockage. I put my finger over one end and sucked on it like a straw to see if it would collapse and it didn't. I'm going to try a new spark plug today. I told my BIL after church yesterday if he didn't want to take it to the Stihl dealer I would keep fooling with it but it might be fall before I figured out what was wrong with it.
    Cannon
     
  16. Cannon51

    Cannon51 ArboristSite Operative

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    New plug made no difference.
    Cannon
     
  17. TuckerSailor

    TuckerSailor ArboristSite Lurker

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    Do you think the coil could be breaking down and the carb wasn't the problem in the first place. Do you have a known good coil to try.
     
  18. Cannon51

    Cannon51 ArboristSite Operative

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    I have considered that. My BIL said it's running exactly like it did before he took the carb apart, so since I changed the carb with no difference I wonder if that was the problem. I have an FS55 parts trimmer but don't know if they use the same coil. Bailey's list a new coil for $136.99 http://www.baileysonline.com/Chainsaw-Parts/Chainsaw-Parts/Stihl/STIHL-IGNITION-MODULE-FS94R.axd That's a lot just to experiment.
    Cannon
     
  19. TuckerSailor

    TuckerSailor ArboristSite Lurker

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    I tried a quick search for a aftermarket coil for a fs94 and came up empty. I don't think I would throw expensive o e m parts at it on a hunch either.
     
  20. Cannon51

    Cannon51 ArboristSite Operative

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    My BIL took it to the Stihl dealer last Monday. Yesterday I saw him using it and went over and ask him what they had to do to it. He said they ordered a Stihl carb for it and that fixed it. I hate when I can't figure out what's wrong with something but it does happen. I appreciate the help non the less.
    Cannon
     

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