1. Welcome Hearth.com Guests and Visitors - Please enjoy our forums!
    Hearth.com GOLD Sponsors who help bring the site content to you:
    Hearthstone Soapstone and Cast-Iron stoves( Wood, Gas or Pellet Stoves and Inserts)
    Caluwe - Passion for Fire and Water ( Pellet and Wood Hydronic and Space Heating)

New Stihl MS390 won't start

Post in 'The Gear' started by Kenster, Mar 27, 2010.

  1. Kenster

    Kenster Minister of Fire

    Joined:
    Jan 10, 2010
    Messages:
    1,593
    Loc:
    Texas- West of Houston
    I bought a new, muffler modified 390 - 16 inch bar - about a month ago. Today is the first time I have tired to fire it up. I mixed a fresh batch of gasoline and 50:1 oil.

    I read the owner's manual instructions several times. I verified that it is set for summer operations. Because it has been sitting dry for over a month I pulled the rope through slowly four or five times to prime it per the book. I set it for cold start. (Ignition switch Lever all the way down.) Pressed the decompression button and began the starting attempt.

    I must have pulled over 100 times now. I don't think it's flooded. I don't smell any gasoline but I did remove the spark plug to check it. It only had the very thinnest hint of oil/gas on it. I wiped it off anyway and reinstalled. No change.

    A couple of questions come to mind.
    (1) The owner's manual in the very first step under starting says to press the Decompression button. Later it says that after it begins to run to Press the Decompression button even though it also says the button will automatically disconnect as soon as it starts.

    (2) When doing the pull start, are you suppose to be pulling the trigger the entire time? With my little Craftsman, I usually don't pull the trigger until right after it begins to fire up.

    So this is quite frustrating. I expected some learning curve with the new saw but it seems like I'm following all the steps. I'd like to conquer this today so if you have time for replies and advise, I'm standing by.

    Thanks!
    Ken in Bellville TX

    Helpful Sponsor Ads!





  2. North of 60

    North of 60 Minister of Fire

    Joined:
    Jul 27, 2007
    Messages:
    2,449
    Loc:
    Yukon Canada
    Your trigger should lock open by itself after you squeeze it when doing the cold start routine.
  3. smokinj

    smokinj Minister of Fire

    Joined:
    Aug 11, 2008
    Messages:
    15,972
    Loc:
    Anderson, Indiana
    choke you done right after hearing the very first burb then flip the chock up one notch then press decomp and fire the sucker up....and to check if its flooded and I bet it is pull the air filter off... and never pull it 100 times it just wears you out...




    """""(2) When doing the pull start, are you suppose to be pulling the trigger the entire time? With my little Craftsman, I usually don’t pull the trigger until right after it begins to fire up."""""

    when you hear a sign of life filp the choke up on knotch no need to hold trigger!
  4. Kenster

    Kenster Minister of Fire

    Joined:
    Jan 10, 2010
    Messages:
    1,593
    Loc:
    Texas- West of Houston
    Jay, I don't know what a "burb" is suppose to sound like. But it's not even close to showing signs of life. It almost sounds as if there is no spark. I just went out for another round. After a few pulls on full choke I moved it up one notch. The sound changed. Maybe a little deeper sound. Still no life and it's just about worn me out.

    My Craftsman always fires up after I pull four or five times on full choke, then move it half choke. First time on half choke it nearly always fires right up. The gent I bought if from on eBay said that I can call him and he will talk me through it. If that doesn't work I guess I'll take it to Western Auto Stihl dealer about 18 miles away on Monday and see if they can help me. The lady that runs that place sure seems knowledgeable based on my visit with her a couple of days ago.
  5. smokinj

    smokinj Minister of Fire

    Joined:
    Aug 11, 2008
    Messages:
    15,972
    Loc:
    Anderson, Indiana
    pull the air filter off and see if it smell of gas real heavy.... it will sound different when you change the setting on the choke I bet its flooded real bad and if so leave the air-filter off and let it air out....the burb on a 390 going to be faint if you will you should get one in the first couple pulls I miss the burb on my 361 more than I care to admit. When you miss it you can pull all day long and it sucks

    burb can be very faint!!!!!!! soft
  6. webie

    webie Minister of Fire

    Joined:
    Feb 21, 2009
    Messages:
    652
    Loc:
    Wisconsin
    Get your self a new plug , skip the decompression relief . It will be a little tuff to pull over but I bet it starts then . Jay I never use the decompression button the first start of the day . That took care of the flooding problem. I havent had a flooded stihl since .
  7. LLigetfa

    LLigetfa Minister of Fire

    Joined:
    Nov 9, 2008
    Messages:
    7,343
    Loc:
    NW Ontario
    I hate seeing the gas dry out of the carb. It tends to dry out and curl the little flapper valves on the impulse pump.

    If you are pulling it with full choke, you just have to be able to smell raw gas at the exhaust if the gas is getting pumped. Loosen the gas cap if it isn't pumping. Could be a plugged vent.

    If it's flooded, pull the plug and stick a propane torch in the plug hole and slowly pull the cord. It will suck in the flame and dry out the inside of the cylinder. It will also shoot out flame so don't be hetting your hair near it. Dry the plug off with the torch too. Try a new plug.

    If you want to see it there is spark, take out the plug, stick it in the boot, and while holding the plug, pull the cord. If it doesn't send a big shock into your hand, you have no spark. Don't do it if you have a weak heart.
  8. oldspark

    oldspark Guest

    You could put just a dab of gas in the carb and see if it fires, the way you described the plug when you pulled it I don't think it is flooded.
  9. Tony H

    Tony H New Member

    Joined:
    Oct 24, 2007
    Messages:
    1,156
    Loc:
    N Illinois
    If you pulled it that manytimes it's flooded or it's getting no fuel pull the cover pull the plug dry it off or replace it. If you cave a compressor use it to blow off the plus let it sit use the air comp or the propane to dry it out. When you go to start it this time set the choke switch all the way down DON"T pull click the switch up one and give it a few pulls.
    For normal starting choke on lever down pull a couple times see if you hear it sound like it might start the burble then flip the lever up one and pull
  10. RowCropRenegade

    RowCropRenegade Feeling the Heat

    Joined:
    Mar 19, 2008
    Messages:
    302
    Loc:
    Southwest, Ohio
    If you can tolerate being shocked, twist out the plug, reattach plug wire and pull with spark plug against your arm. If you don't jump when you pull it, it narrows it to electrical. If you do jump, my best guess is breather.
  11. Kenster

    Kenster Minister of Fire

    Joined:
    Jan 10, 2010
    Messages:
    1,593
    Loc:
    Texas- West of Houston
    Okay... I got it started. I checked the plug three times. It never seemed that wet but I wiped it off well each time. I took off the air filter. It had a faint smell of gasoline but not real strong. The carb looked clean and had very little gas.
    I put it all back together. With the switch in the "Off" position. I pulled it a few times, which I believe is a method to help drain a flooded system. I then put it on the "Run" position and pulled a couple of times. It sounded like it wanted to start. I put the switch on the "warm start," which I believe is sort of a half choke (?) and it fired right up!!

    It blew smoke for a few seconds then it cleared up. Ran like a champ. I'm used to a little 32cc Craftsman so this MS390 with 64CC and modified muffler sounds like the difference between a Cushman Scooter and a big Harley.

    Now, I don't want to have to go through this every time I do a cold start. I think what I need to do is, with full choke, pull it a few times then move it to half choke, which should allow it to start up. Right?

    Not sure what to do about the decompression button. Don't use it for the first start of the day? After I got it started today I did a little bit of light cutting. I'd sit it down for a while and come back and start it up again and it would fire right up. I never touched the decompression button again. So, I'm not sure just when I should use it.

    Thanks for the suggestions and I would appreciate any follow up advice you can give.

    Ken
  12. webie

    webie Minister of Fire

    Joined:
    Feb 21, 2009
    Messages:
    652
    Loc:
    Wisconsin
    I am hopeing for the best for you , This is the saw you got off of EBAY that had a muffler mod done to it ? You may want to pull the muffler off and take a look at the piston . Hopefully the guy didnt lean this thing out to much and make scrap out of it . Your little gas on the plug makes me kinda wonder . If your compression is up to snuff . I would say after this if you still cant get it going you might want to test the service at that Stihl dealer you found close by .
  13. thinkxingu

    thinkxingu Minister of Fire

    Joined:
    Jun 3, 2007
    Messages:
    1,075
    Loc:
    S.NH
    Starting method for every Stihl I've ever run:

    When COLD:
    1. Make sure bar oil/gas tanks filled
    2. Pull trigger and put lever all the way to full choke
    3. Pull over 2-4 times until you hear a 'pop' (like it will *almost* start)
    4. Put lever to run position
    5. Pull over once
    6. Cut wood

    When HOT (within a few hours even):
    1. Put lever to run position
    2. Pull over once
    3. Cut


    S
  14. webie

    webie Minister of Fire

    Joined:
    Feb 21, 2009
    Messages:
    652
    Loc:
    Wisconsin
  15. southbound

    southbound Minister of Fire

    Joined:
    May 26, 2008
    Messages:
    733
    Loc:
    mid south tn

    All I have to add is it does not take a lot of fuel to flood one of these out...Yes I will admit to flooding out my 290 more so when it was new to me and the plug was never that wet and the smell of fuel was never that strong...

    Also for the decomp valve push it in before you lock the trigger and then when you hear the almost start you move up the switch and it should fire right up.....
  16. Kenster

    Kenster Minister of Fire

    Joined:
    Jan 10, 2010
    Messages:
    1,593
    Loc:
    Texas- West of Houston
    You don't mention ever using the half choke position. Do you not ever find it necessary to do so?
  17. oldspark

    oldspark Guest

    My 045 starts just like that and has for 30 years, have not figured out my 028S i bought a year ago, my 09L needs a shot of gas in carb after it has set much over a few days.
  18. thinkxingu

    thinkxingu Minister of Fire

    Joined:
    Jun 3, 2007
    Messages:
    1,075
    Loc:
    S.NH
    Kenster,
    I should have made it more clear: when you hear the 'pop' after 2-3 pulls on full-choke, you pop it down to half which keeps the trigger still pulled. THEN you pull it once, wait a second, and hit the trigger.

    Run.

    S
  19. southbound

    southbound Minister of Fire

    Joined:
    May 26, 2008
    Messages:
    733
    Loc:
    mid south tn
    fuel and oil

    set the chain brake

    push in decompression valve

    lock trigger by pulling trigger and moving switch all the way down

    pull until it almost starts

    move switch up one notch

    pull till starts 1 or 2 pulls

    at this point you will have to pull the trigger to unlock it and the switch will go from choke to run on it's own you then can release the chain brake and start cutting....

    Next start of the day

    set chain brake move switch down one notch to run and pull cord...
  20. WNCburner

    WNCburner Member

    Joined:
    Nov 12, 2009
    Messages:
    60
    Loc:
    Western North Carolina

    This is exactly how my MS 361 likes to be started. The first few times I tried to start it, the saw flooded and I was very frustrated. The "blurp" on my saw was easy to miss because it is such a minor event--not at all like my older Stihls which actually run for a few seconds on full choke. It's like the saw fires for one stroke of the piston, very subtle and quiet event. Sometimes I don't even hear it, I just see the decomp button pop up and know it's time to switch to half choke.
  21. smokinj

    smokinj Minister of Fire

    Joined:
    Aug 11, 2008
    Messages:
    15,972
    Loc:
    Anderson, Indiana


    Yea!now it will get easier each time....3-4 pull maxium
  22. webie

    webie Minister of Fire

    Joined:
    Feb 21, 2009
    Messages:
    652
    Loc:
    Wisconsin
    Just another idea here if you want a helping hand without useing the decompression release . Install an elastostart recoil . It helps alot . I have them on all my saws 026 on up . only the 460 do i use the decomp alot , or if it gets towards the end of the day and I am tired after starting the saw about 50 times .
  23. Kenster

    Kenster Minister of Fire

    Joined:
    Jan 10, 2010
    Messages:
    1,593
    Loc:
    Texas- West of Houston
    Do these saws require no priming for a cold start. Some of my other equipment has a little soft, round bulb that I pump a few times to prime it before starting. The owners manual says something about pulling the rope slowly a few times with the switch off to prime it but I thought that was for the first start EVER, not the first start of the day.

    Thanks for all the help and suggestions! I'll need a little practice being able to recognize the "Burble" to avoid flooding it all the time.

    I decided before I sent this post I'd go out and try to fire it up today. I did use the Decompress button. On the third pull on full choke it started to fire, not just a pop. I moved the switch to half choke. One pull and it fired right up!

    Obviously, yesterday's flooding was operator error, not mechanical malfunction. I used to teach technology to other teachers. We had a term: PICNIC. Problem In Chair. Not in Computer.

    Cheers!
  24. smokinj

    smokinj Minister of Fire

    Joined:
    Aug 11, 2008
    Messages:
    15,972
    Loc:
    Anderson, Indiana
    no priming...you have it down now just rember its going to burb within the first 3 pulls I will go ahead and move the choke switch after 3 even if I didnt think it did...
  25. SPED

    SPED New Member

    Joined:
    Dec 31, 2007
    Messages:
    363
    One thing my stihl dealer told me when I bought my 290 was never pull more than 4 times with the lever all the way down on full choke. He said he picked that up right from a stihl rep. So even without a pop he said move it up a notch after 4 pulls. So far has worked for me but mine isn't even broken in yet.

Share This Page