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04-16-2010, 10:50 PM
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Weed Eater carburetor repair
After about 8 years of zero maintenance (except Stabil in the gas) my Echo string trimmer is starting to run rough and won't accelerate smoothly. It has the standard 21cc motor with a Zama carburetor. What is the best way to clean/rebuild this unit?
PS - the spark plug is clean and gapped.
Thanks,
Jeff
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04-17-2010, 07:48 AM
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String trimmer
First determine the model #, this can be found on the serial # plate. Next remove the muffler, then remove the exhaust outlet to look the arrestor screen. If it is plugged at all, lay it on a brick and fire uo a plumbers torch, concentrate the flame on the screen and all the carbon will be burned off. Next look into the exhaust port, slowly move the piston up till the port is blocked, then take a toothbrush handle and grind to to fairly sharp chisel point and use that to scrape out all the build up in the port. resemble the muffler and remount it on the machine, try starting and accelerating. This is the most common failure. Next check the fuel supply line for cracks, also the
the purge line and the tank breather line - cracks are not good. May want to replace the fuel filter and breather vent at this time. If these steps don't correct your problem, let me know and we'll walk thru the card.
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04-17-2010, 09:51 AM
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Just to be safe I'd replace the spark plug. Sometimes they can look great and still not function perfectly (had that happen on a 150 Merc last year).
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04-17-2010, 10:00 AM
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He has spark. Sometimes when replacing a functional plug you get a non-functional new plug. I've had that happen too.
If it ain't broken . . .
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04-17-2010, 10:26 AM
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Try adding some Sea Foam to the fuel everytime you fill the tank.
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04-17-2010, 12:34 PM
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Quote:
Originally Posted by kalei
First determine the model #, this can be found on the serial # plate. Next remove the muffler, then remove the exhaust outlet to look the arrestor screen. If it is plugged at all, lay it on a brick and fire uo a plumbers torch, concentrate the flame on the screen and all the carbon will be burned off. Next look into the exhaust port, slowly move the piston up till the port is blocked, then take a toothbrush handle and grind to to fairly sharp chisel point and use that to scrape out all the build up in the port. resemble the muffler and remount it on the machine, try starting and accelerating. This is the most common failure. Next check the fuel supply line for cracks, also the
the purge line and the tank breather line - cracks are not good. May want to replace the fuel filter and breather vent at this time. If these steps don't correct your problem, let me know and we'll walk thru the card.
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It's an SRM 2100. There is no carbon build up in the exhaust system. The air filter is clean but oily. I ran it without the filter - no change.
While I had it running a played with the adjustment screws. The hi speed adjustment did not change any thing but the lo speed adjustment helped with acceleration. According to the manual the lo speed screw does help with acceleration. It's much better now but not perfect. I couldn't see any cracks and I didn't look at the fuel filter. I think I'll replace both filters. Any other thoughts?
Thanks again,
Jeff
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04-17-2010, 01:21 PM
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While your changing fuel lines get a can of carb clean with the red straw for the nozzle and shoot it in the fuel inlet and return ports , careful it doesn't shoot back out in your eyes ! Probably some gum or a bit of microscopic dirt in there somewhere. If necessary you can remove the needle screws and clean in there too , then readjust the carb from scratch. Zama has a guide for this here: USA Zama : Service Tips
Good luck and let us know how it goes,
Ray
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04-17-2010, 04:26 PM
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Thanks Caseydog,
That and the link are very helpful.
Jeff
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04-17-2010, 05:26 PM
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I agree with Kalei - except for the spark arrestor screen. Remove it and throw it away. (Same goes for any two cycle engine). You might check the fuel filter inside the tank. Sometimes they get out of location and suck air - I've had that happen.
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04-17-2010, 07:44 PM
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A lot of two stroke engines are giving trouble these days with the 20% ethonol available at most gas stations. There are still some gas stations that don,t sell the ethonol mix. After you get it fixed try to use gas without ethonol. I use ethonol free gas in all my two strokes in my lawncare buisiness, Some of the other companies that just buy gas anywhere are having a lot more trouble than I am.
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04-17-2010, 07:50 PM
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The only problems I've had with either of my weed eaters is the fuel lines get brittle and break. When the line inside of the gas tank that has the filter on the end of it breaks the carb has a hard time getting fuel.
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04-17-2010, 09:08 PM
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I've rebuilt several of my small engines in the last year. First time in 10 for some of them. I firmly believe it's the enthanol in the gas.
That being said, I ordered the "kit" and rebuilt it myself. Quick and easy. If you're going to go to the trouble to take it apart and clean it, might as well put in new parts.
good luck,
Munster
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04-17-2010, 09:29 PM
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Try "tacreload's" suggestion on the SeaFoam fuel cleaner before you get too far into it.
Works like a charm.
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04-18-2010, 09:58 AM
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The other thing to look at is what type/brand of 2cycle oil are you using? My recommendation is to match the 2 cycle oil to brand name on the unit. In my job we have to run a series of emissions tests on the units we normally get better results following the above.
As for the comment on removing the spark arrestor and throwing it away, In my job I can not even suggest doing that without getting trouble, take that with a grain of salt and do it either way.
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04-18-2010, 01:00 PM
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I have a "Stihl" weet eater that was the same way. Stihl service said I needed to buy a "carbureator kit", it was just 8$, and with a new membrane and new gaskets and 20 minutes of work this thing ran and still runs like new.
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04-18-2010, 02:17 PM
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Quote:
Originally Posted by Hermann
I have a "Stihl" weet eater that was the same way. Stihl service said I needed to buy a "carbureator kit", it was just 8$, and with a new membrane and new gaskets and 20 minutes of work this thing ran and still runs like new.
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Sounds like a 2 beer job to me
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