String trimmer won't idle...please help!

kentc80June 4, 2010

Hi all. I am working with an Echo GT-1100 string trimmer. I must warn you ahead of time, I will be somewhat long-winded to be as descriptive as possible. The problem at hand is that my trimmer won't idle. It knocks off after aprox. 10-15 seconds of runtime after being started. After considering various small factors, I am down to adjusting the carburetor. The trimmer seems to run fine at WOT. I have run the idle speed up trying to gain some room to work with to the point that it sounds like it's at part throttle, with the head spinning also, while idling. I honestly believe, but am not certain, that I have the idle mixture adjusted about right. For the duration of time that it does idle, no more than a 1/4 turn to the rich causes it to sputter slighty, while no more than a 1/4 turn to the lean causes the engine speed to fall until it knocks off sooner than its' current setting. Having this said, what would anyone recommend my next step be? I will happily answer any questions that I am able to. Any and all responses are greatly appreciated. I will respond asap. Thanks a million!!!

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ewalk

I'am more familiar with chainsaws but have worked on my (Old) Weed Eater for yrs. There all temperamental especially the newer (EPA) regulated units i have been informed. I assume you have full , half and open choke setting and you use them properly . I would suggest you 1st check fuel tank for proper level and mixture (don't laugh) then for a fuel filter and ensure it is not dirty , then check all full lines are tight and in good condition. Next check condition of your Spark plug . All ok there then remove the jets High & Low and inspect needles (bent , worn) ? if ok give a blast of carb cleaner in both . Reinstall tighten carefully till they seat. Then adjust both at 1-1/4 turns out. Play with the high speed 1st you may find it better around 1-1/2 out once you reach the highest rpm @ WOT turn it back in just a touch. Next adjust the Low Speed jet until there is no hesitation upon throttle response. The idle adjustment is what ever you wish I have mine a little high to ensure the head just barely spins . If the above does not help you may need a carb kit via your local dealer ! Good Luck Bro !!

    Bookmark   June 4, 2010 at 5:29AM
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kentc80

Thanks so much ewalk for your reply. I believe most if not all of the simple stuff exterior of the carburetor is in good working order, but I will double check them all sometime Saturday. If all checks out okay, I will move on to inspecting the mixture screws and spraying the seats out with Gumout or an equivalent. After reseting the screws, if it still acts the same, I will probably go ahead with the carburetor kit, which is kind of what I've been expecting all along, but wanted to avoid if possible. I will let you know of the results. Thanks so much for the help!

    Bookmark   June 5, 2010 at 7:39AM
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ewalk

No Problem Kent , happy to assist. P.S. On the High Speed Tuning once highest RPM is reached turn out the Jet just a little not until it gallops , just to ensure you are no running to lean . I doubt you run the unit wide open for extended periods of time such as Chain saw usage , but it never hurts to run a little rich , plugs are cheaper then rings or pistons lol. Sorry for any confusion on that part . Let us know how it goes and Welcome aboard Chow Bro !

    Bookmark   June 5, 2010 at 8:40AM
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masiman(z7 VA)

This is one of the best explanations of how to tune a saw:

Madsens Tuning Guide

    Bookmark   June 5, 2010 at 2:06PM
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ewalk

Excellent Tuning Guide Mas , love the reference to Blubbering which I usually refer to a Dieseling or Galloping lol . I normally do the idle adjustment last once both high and low jets have been fine tuned and have the idle just high enough that the chain attempts to roll , this assists with a better cold start idle since the idle is always affected by the H&L Jet Adjustments at least on my saws. I especially like the portion where it advises of proper fuel tank levels and air cleaner condition prior to tuning , Great Post !

    Bookmark   June 6, 2010 at 9:47AM
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strelnikov(NE IL)

Make sure the spark arrester screen in the muffler is clean. If it is plugged up the engine won't be able to breathe and will not idle properly no matter what you do to the carb.

    Bookmark   June 7, 2010 at 9:57PM
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kentc80

Hi all. I was able to spend some time on the carburetor today and it looks like I'm looking for a kit. One question, though. Does anyone know how I should go about setting the needle valve lever? I would hate to get it back together and it run too rich or lean all of the time. I look forward to all sugestions. Thanks again!

    Bookmark   June 7, 2010 at 10:09PM
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masiman(z7 VA)

Thanks ewalk. I am in no way really good at tuning. I have to read it each time I do it (2 or 3 times/year). I really need to get a tach per their recommendations. More toys ;).

I don't know if you or others noticed but on that page, they have a link to a sound file of how a saw sounds being tuned. It's quite helpful in case any of the terms are not familiar.

As for setting the needle valve lever, more experienced folks may have more input than me. I have not messed with my needle valve levers. If I had to, I would not know how to set it. I think you bend the lifter to adjust its behavior, but I am not positive on that. Of the few carb rebuilds I have done, it was gaskets and diaphragm only. The other stuff went to the parts bin.

    Bookmark   June 8, 2010 at 5:32PM
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ewalk

Mas you definitely need a tac when you get into Porting and Mod Hot Saw Tuning ! Great Investment if so . As far as the Needle Valve Lever each application is different , Kent will have to invest some time researching a Shop Manual or recommendation from his local dealer , if he has changed the original positioning of the tab .

    Bookmark   June 9, 2010 at 5:31AM
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dlb014_aol_com

my echo gt-1100 trimmer wont idle either. i am pretty talented, but this thing beats me. it starts up and runs fine at full throttle. when you release the throttle, the engine begins to run lean and stalls. please help!!!

    Bookmark   September 5, 2011 at 4:09PM
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ewalk

Main jet has some dirt or varnish or the low speed jet requires some tuning . Both H&L Jets should be 1-1/4 to 1-1/2 turns out from bottomed. Some fuel cleaner would be a good investment also .

    Bookmark   September 5, 2011 at 6:03PM
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MerlinG

Having lot the same problem with a Husky 128 LD.about 3yr old. Last season found primer bulb cracked. replaced it and trimmer would not prime. Found fuel lines had basically disintegrated. Replaced, still wouldn't prime.figured carb was gunked up. This season I replaced the carb and gasket. Replaced the fuel lines with non-permeable lines. Replaced fuel lines. Using no-ethanol fuel with synthetic 2-cycle oil. Fuel is fresh and blew fuel filter out with carb cleaner.

Now primes real easy, starts real easy. Runs for a minute or two at open choke. With about a 30 second warm up a half choke. Then dies especially when I give it some throttle for some cutting. Will restart but still won't run very long. Any suggestions. First year and half of service was great. Seldom had to run full throttle. Had a Troy built 2 cycle and 4 cycle before this was so much better. Now my Troy built mower with a Honda engine that's a whole different story!

    Bookmark   May 20, 2014 at 11:32PM
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the_0utsider

Kentc: being you have the idle mix set, did u try lowering the idle screw? if not, as u adjust that screw, set the idle mix screw toward the rich side.
Another possibility- look behind the flywheel and under the pull start, do u see it collecting alot of dirt (sticking to leaking gas\oil). I've seen several echos where the shaft seal leaks=lower internal pressure during the down stroke=needs to run faster to maintain internal pressure.

strelnikov: i find a clogged spark arrester (from my experience) stops high speed when u have a high volume of air but idles fine.

ewalk: of course the main jet u speak of cleaning is not for the idle being his high speed is fine.

    Bookmark   May 30, 2014 at 1:40AM
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