String Trimmer - post re-build problems

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  #1  
Old 07-06-06, 10:22 AM
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String Trimmer - post re-build problems

First off, please forgive my ignorance as I have no experience working on anything mechanical. But, it sounded like fun so hereís what happened.

I have a Weed Eater brand sting trimmer. (XL-20T). Itís about 8-10 years old. At the end of last year, it kept getting harder and harder to keep running with the choke off until finally I couldnít start it at all. So this year I bought a re-build kit for the Warblo (I think) carburetor. I did the work (based on tips I read here) and now it starts great and seems to idle fine with the choke off. The problem Iím having is that the throttle response is horrible. I pull the trigger and it takes a few seconds to ďbuild-upĒ steam and when it finally seems to be running on full throttle, I have no power. Meaning that when I put it to the grass, it almost dies unless I move real slow. And after about 10 minutes it dies and I canít get it started again. But the next day it starts fine and then it all happens again. I think, and please feel free to correct me, that itís getting flooded. The only thing I can think of that would cause this (and here we get into technical names I donít know) is the little rocker assembly in the carb that attaches to the inlet needle (in a four stroke I think there would be a float doing the same thing as this little strip of metal). Anyway, there were no instructions with the re-build kit so I may have messed something else up. If this is the problem, how and to what specifications do I adjust that plate.

Also, just for more information, Iíve read a lot around here about adjusting the TWO screws on the carburetor (H and L I believe). I have two screws on mine but one is marked with both the H and L. The other screw has a big spring wrapped around it and adjusts the position of the throttle lever at idle. In case this has any bearing on you solutions.


Thanks for the help and sorry for the long post.

Aaron
 
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  #2  
Old 07-06-06, 03:45 PM
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You have been setting here all day without a response, if the trimmer is 8-10 yrs old fuel flow issues come into play(if the items haven't been replaced),the intank fuel filter/pickup is dirty and will not allow flow or the fuel lines have deteroriated to the point of collapse or cracking. Have a nice day, Geo
 
  #3  
Old 07-07-06, 06:39 AM
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Thanks for the reply. At the same time, I replaced the fuel filter and fuel line. As well as the spark plug. Any other thoughts? (besides, "buy a new one")
 
  #4  
Old 07-07-06, 09:01 AM
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Normally I would totally agree with your last comment. Since you have already thrown parts and labor worth half the price of a new one into yours, it becomes a challenge. If you think it's flooding, check the spark plug after it dies. If it's wet and/or carbon-ed, the carb needs adjusting.
I don't profess to be an expert on these. When my 10 year old McCullough died this year, I just watched for a sale, bought a new one, then tore the oldie apart just to see how it was constructed. $100 for a new one whose line advance actually works sure beat pulling out my few remaining hairs.
 
  #5  
Old 07-07-06, 10:40 AM
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So, any thoughts on why I think it's flodding (read above). I'm wondering if adjusting that float-lever assembly (thingy) would help it or not? And if so, to what specifications.
 
  #6  
Old 07-07-06, 11:21 AM
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Did you check the muffler to see if it is stop up with carbon,take it off and check the spark arrester screen if it has one,if not try running it just a few seconds to see if it will reb up.


Jerry
 
  #7  
Old 07-07-06, 01:22 PM
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Thanks, I'll try that this weekend. I only have internet access at work so I'll post a reply monday. Anything else?
 
  #8  
Old 07-07-06, 02:30 PM
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If I'm not mistaken, your model trimmer should have four tiny outlet ports for the exhaust to escape the muffler. These tiny holes typically become encrusted with carbon build-up over the years and needs to be scraped clean periodically. I'll bet this is your trouble.
 
  #9  
Old 07-07-06, 08:27 PM
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You may have some carb problems that need attention but you can try some of these before you dismantle it.

If you haven't adjusted the mixture screw I would try that to get the best response possible. Also what is the gas/oil mix you're using? The older ones have the heavier oil ratio. You can gain a little by going to a lighter oil mix.

Also, if you haven't already done so I would lube the drive cable. After ten years it wouldn't hurt. When you have the drive tube off start the engine and see how the engine response is without the trimmer load on it. Something may be binding down in the head or you may have a worn out liner.

Hope this helps
 
  #10  
Old 07-07-06, 10:30 PM
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Weadeater/Poulan mufflers are held on by springs connected to the cylinder and on most of them the spark arrestor is inside the muffler which cannot be taken apart.

Carburetor: check the metering diaphragm (the side held with 4 screws) and see if you installed the diaphragm before the gasket.
The gasket should go on the carb, and the diaphragm should go on the gasket and then the cover.
Make sure that the metering lever is level with the carburetor floor.

Adjustment: The initial adjustment on both H and L is 1 !/4 from lightly closed position. Once the engine is running, hold the trigger wide open and "SLOWLY" turn the H screw in until you hear the engine smooth out then back off just a hair.

It should wind out as soon as you squeeze the trigger, if not the idle screw (large screw with spring around it) is too low and needs to be turned in, turn it in 1/4 of a turn at a time and keep testing.
 
  #11  
Old 07-10-06, 07:10 AM
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Wow, thanks for all the replyís. Jsouth and puey61 - I took off the muffler and as Mikesmalleng said, itís all one piece but everything look clean behind the muffler. Would replacing the muffler make any difference? It sounds fine and looks fine but I have no way of knowing if itís gummed up inside.

Marbobj, I lubed the drive cable, although it didnít fix my problem, it definitely needed it.

Mikesmalleng Ė Thanks for all the tips, and brilliant explanations. I guess Iím down to taking the carb back apart. Which is fine. Iíll let you know about the metering diaphragm. This sounds like somewhere I might have screwed up. Also, thanks for:

ďMake sure that the metering lever is level with the carburetor floor.Ē


This was exactly what I wanted to know in my initial post.



I have to tell you guys, Iím driving my wife nutís working on this thing, but Iím having a lot of fun. (Of course, I donít have any customers badgering me and if I never get it fixed it doesnít really matter). Now itís more the challenge of fixing it.

Iíll try all your suggestions tonight. And let you know.

Thanks, again.

Aaron
 
  #12  
Old 07-11-06, 09:08 AM
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Hi All,

Thought I'd let you know that I took the carb back apart to check the stuff mentioned above. The casket was correct but the "metering lever" was a little high (I think, it was so close I couldn't really tell so I just sorta nudged it). Changed that and cleaned it all again and carefully put it back together and it seems to be working just fine. I'm not sure if it was the metering lever, or something I accidentely fixed or what but it seems fine (Although I haven't really put it to hard work yet). Anyway, thanks for all the great help.

Aaron
 
  #13  
Old 07-21-06, 03:06 AM
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Your Weed Eater Has No Float In It Thats What Makesit An Impulse Diaphram Type Carborater. If It Lacks Power It Is Probably A Clogged Resinator In The Muffler,the Muffler Can Be Seperated And Screen Can Be Cleaned,some People Have Even Left The Resonator Out As It Will Increase Power However It Will Be Louder. You May Even Want To Experiment By Turning Screw An Eighth Turn At A Time To See If Mixture Adjustment Solves Problem.note Original Screw Position Before Turning.
 
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