# loss of power at full throttle



## Dan E (Aug 10, 2006)

I have a Echo PB-260L that is about 2 years old. It starts fine, idles well but does not build to the same full power when the throttle is pushed wide open as it used to. I have replaced the fuel filter, air filter, rebuilt the carb (Walbro), new spark plug, decarbonized the exhaust port and removed the spark arrestor. It does run better with the spark arrestor removed: at full throttle it has the power and the engine has wound up to the full RPM''s,but she slowly loses power and dies after 30 seconds or so. If I remove the air filter all seems well. Seems to me that it has to be a fuel/air mixture issue. Help??


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## peppy (Jul 19, 2006)

Is the carburetor adjusted properly?


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## Dan E (Aug 10, 2006)

There is just one set screw on this carb. It sets the idle speed as far as I can tell, and she idles fine. Thinking that I may take the carb apart again and clean it / soak it. Maybe the needle valve is on too tight??

Thanks for the suggestion.


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## truenorth777 (Mar 28, 2006)

Sounds to me like it is the high speed idle screw this is where all the gas comes in at a higher throttle.

If its a bowl type carb the high speed idle screw is what holds the bowl onto the carb body.

Make sure you have no gas running into the carb before taking it apart than

Take the screw out, clean the bowl out, use a tooth pick to clean out all the ports in the carb and in the needle, it would also be good to put it into some carb cleaner over night to get rid of all sedimate (make sure you remove all plastic pieces or the cleaner will eat it)

Than put it back together and it should run like new.


Hope this helps.


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## Dan E (Aug 10, 2006)

It is not a bowl type carb... diaphram type ? When I did the carb rebuild this morning I replaced 2 sets of "gaskets" that were each a combo of a thin and a thick gasket. One of these contained a diaphram that sits over the opening from the primer bulb (i think...) Maybe I just did not get all of the crud out.?


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## geogrubb (Jul 28, 2006)

It is also important that the gasket and diaphgram are installed in the correct sequence. Have a nice day. Geo


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## Dan E (Aug 10, 2006)

The fact that the symptoms are the same after doing all that I have done as compared to before the changes suggests that my rebuild of the carb is ok, although I might stillhave dirt/crud somewhere. I'll tear into it this weekend. Question... can I still reuse all of those gaskets since have only run it briefly, or does the fact that I have torqued the screws downrender them susceptible to leaks? I'm thinking the later and gotta break lose with the big $4 for another rebuild kit :dude:


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## peppy (Jul 19, 2006)

Dan E said:


> does the fact that I have torqued the screws downrender them susceptible to leaks? I'm thinking the later and gotta break lose with the big $4 for another rebuild kit :dude:


Yeah... that usually is what you have to do once you compress it. Better to be safe than sorry


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## Dan E (Aug 10, 2006)

Still stumped by this... My 2nd rebuild of the carb resulted in a worsening of the situation. It starts fine, idles with the choke closed, but when I go to move the choke to the run position (open) it dies. I have checked the compression (80 psi), run it without the muffler (clogged cat? but still the same result.) I must be doing something wrong in the carb rebuild. My gaskets mirror those that I removed the first time (original ones), I have checked the order of the gaskets and all seems fine. There is a small rubber o ring in the rebuild kit, along with a couple of gaskets that I am assuming are just part of the generic rebuild kit that walbro puts together for these carbs. Or am I missing the location for the small rubber o-ring? These are the things I have replaced on the carb: 2 sets of gaskets, screen, needle valve and lever that holds needle valve. I have soaked the bottom of the carb (no plastic parts) in carb cleaner and blown compressed air though all (?) holes.... Any thoughts?? Sorry for the long winded response...


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## repair_guy (May 9, 2004)

Hello Dan E,I've gone over your post and what others has sugested thinking about your problem.Your carb is a Walbro WYJ series,which there are many differant styles,BUT.... they all basicly the same and all have a lot of enterchangeble parts.and a carb.kit comes with enough gastets and diaphragms to rebuild them all.So make sure that all of the gastets and diaphragms match the ones that you pulled off.And the mettering lever is about 1/64" below straight edge run across the top of where the mettering lever goes.
And If you're sure that the throttle cable is adjusted to where when you mash it,and it opens the throttle fully then sounds to me that it may be running just a little bit lean,and that's why it runs like crap when at WOT.
Look at the top of the carb.(where the throtttle cable hooks).You'll see an hour glass shaped piece of metal with marks all the way around it,with a screw in the middle of it.This is the only adjustment that this style of carb has.Turn this screw one click at a time CCW trying to rev the engine up each time until you get it right.


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## hankster (Jan 1, 1998)

If your compression is only 80 psi then that is too low. You have other problems then the carb. Look for a scored cylinder/piston or stuck ring.


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## Dan E (Aug 10, 2006)

Thanks for the advice...The parts place has sold me a rebuild kit with code number of K20-WYJ... this is a Walbro, so I guess that you are right about the type of carb. I do not see any hourglass shaped piece on the top. There is a black plastic piece that is the topend of the butterfly valve that rotates and hits a low idle adjustment screw and at the high end another plastic piece that looks integral to the top. No adjustment other than the low idle screw. 
The engine begins to splutter and die when I give it throttle. It started out with it dying at WOT, but my imperfect attempts at rebuilds have resulted in it now spluttering and dying whenever I give it gas. Maybe a whole new carb is in my future...


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## repair_guy (May 9, 2004)

Dan E,click on my name and send me an email with your email address and I'll be glad to send you the picture that I have of your carb.to help you locate the adjustment screw.


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## Dan E (Aug 10, 2006)

hankster said:


> If your compression is only 80 psi then that is too low. You have other problems then the carb. Look for a scored cylinder/piston or stuck ring.


 Hankster, what should my compression be? over 100? If it is a piston/cylinder/ring problem then what are the reasons for this (only 2 years old!! solutions?

Thanks


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## hankster (Jan 1, 1998)

I don't have the specs on hand for the Echo engines but less expensive engines (like Poulan and MTD) should have at least 90psi and more expensive engines generally should have 100+. Chain saws should have no less the 125. I don't believe that model of engine has a compression release which would change those numbers.

Generally piston/cylinder scoring is due to improper fuel mix, normally not enough oil. Could also be carbon buildup due to running too rich or the wrong kind of oil which can cause the ring to stick or the carbon can score the piston/cylinder. Also, overheating from poor air flow caused by lack of cleaning can cause any of the above.


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## Dan E (Aug 10, 2006)

Hey everyone, just wanted to bring the list (and archives) up to date on this issue... reolved!! The Echo blower is working and running like new. Thanks so much for the help of the list. I didn't in the end mess with the high speed needle valve, but just soaked the carb minus whatever plastic pieces I could get off. So it looks like it was a small gummed up hole somewhere. I'll have to test my compression again... I actually tested it when the engine was cold, and to get a better value I should have warmed it up a little first,no??

Thanks again for all the help. 

Dan


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