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Echo CS-590 didn't pass a vacuum test!

Discussion in 'Chainsaws' started by TJ the Chainsaw Mechanic, Jul 24, 2016.

  1. TJ the Chainsaw Mechanic

    TJ the Chainsaw Mechanic Old Homelites rule!

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    So, guy brings one in saying it doesn't want to idle. If I remember right this thing is under 2 years old. Holds pressure very well, but it leaks vacuum. I put wd-40 on the seals and it's not being sucked through. The saw runs fine at the top end, but after idling for over 30 seconds roughly...it idles Majorly erratic. We're talking Super lean....fine...super lean....fine....super lean....fine....super lean...fine......and it doesn't matter weather you have the Low mixture screw as far as 3 full turns out. It will still do it. The Impulse hose seems to be a little loose on the carb nipple..but I don't remember them being super tight anyhow. Any ideas?
     
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  2. smokey7

    smokey7 Pinnacle OPE Member

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    Was it fairly warm when you checked vac?
     
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  3. Simondo

    Simondo Pinnacle OPE Member

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    Is that a HDA 268a carb on it ? or any HDA that has a accelerator pump ?
     
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  4. trooney

    trooney Admitted Woodaholic

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    vacuum leak could come from alot of places, I don't have to tell you that. If its losing vacuum I would find out where if it were me. If it still does it after that I would suspect something in the carb is not functioning right, maybe check valve?
     
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  5. sunfish

    sunfish Pinnacle OPE Member

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    I though this saw was awesome, never had any issues & a 5 year warranty???
     
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  6. TJ the Chainsaw Mechanic

    TJ the Chainsaw Mechanic Old Homelites rule!

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    Nope, had not been ran that day that I am aware of. I ran it then let it cool off for awhile and it leaked the same.
     
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  7. TJ the Chainsaw Mechanic

    TJ the Chainsaw Mechanic Old Homelites rule!

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    Correct, HDA268A. I did rebuild it as the fuel pump gasket was pretty stretched. Takes a throttle fine...unless you idle it for any length of time...then it will do the symptoms above. If you give it throttle it'll bog a little then full throttle as normal.
     
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  8. TJ the Chainsaw Mechanic

    TJ the Chainsaw Mechanic Old Homelites rule!

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    I do my vacuum/pressure testing with the carb off and a testing flange in place. Then I block the exhaust with a rubber gasket using the muffler to compact it. Then I block off the impulse hose.
     
  9. TJ the Chainsaw Mechanic

    TJ the Chainsaw Mechanic Old Homelites rule!

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    I own a CS-590 as well....never have had problems yet.
     
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  10. Simondo

    Simondo Pinnacle OPE Member

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    Photo0724.jpg
    You know on the Stihl MS 361 the carb has a brass plug in the case where the throttle rod passes through ? behind is the accelerator pump ...I wondered if the HDA 268.... A = (pos means accelerator pump) on the Echo has the same as iv had the symptoms on a 361 and a 346 xp very like you are having. That dam little pump (hidden from view) can be a right shi@t. Pic of carb of a 346 without brass plug and pump in place ,but you get the idea.
     
    Last edited: Jul 25, 2016
  11. TJ the Chainsaw Mechanic

    TJ the Chainsaw Mechanic Old Homelites rule!

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    Thanks, I will see about pulling the plug out. Could very well be some crap in there for sure or something else.
     
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  12. Simondo

    Simondo Pinnacle OPE Member

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    O ring on the plunger breaks down and the plunger sticks ...watch for the spring !!
     
  13. fordf150

    fordf150 Pinnacle OPE Member

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    Check the decompression valve. They will hold pressure but leak under vacuum. From what Carl was telling me about the POS base gaskets I would also pay a little more attention to them.
     
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  14. TJ the Chainsaw Mechanic

    TJ the Chainsaw Mechanic Old Homelites rule!

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    Thanks guys, Will look into it today hopefully.
     
  15. TJ the Chainsaw Mechanic

    TJ the Chainsaw Mechanic Old Homelites rule!

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    Hey guys! Ended up being the compression release. While vacuum testing I could pull and turn the release and it would stop leaking vacuum. I pulled the release and soda blasted it; popped it back in and the saw hold pressure and vacuum like never before. Least it idles nice! Little tuning and she ran like a top. Thanks for the help!

    Oh yeah, @Simondo There is no accelerator pump on the carb of this saw. I looked and there was no plug.
     
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  16. CoreyB

    CoreyB Yep I am your neighborhood coffee man

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    That is good news. Nice when it is a simple easy fix.
     
  17. Simondo

    Simondo Pinnacle OPE Member

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    Good outcome ...much better than the work (or cost) needed to sort out a carb with the acc pump!
    I will remember about the de comp in a wonky idle situation myself for future.
     
  18. trooney

    trooney Admitted Woodaholic

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    Thats why I dont like the little buggers. On my 066 and up they are good to have but I've not got to the point yet that they are neccessary on an 026! Lol If I get a leak of any kind when I'm p&v testing I spray the whole saw down to find it. In this 1 saw that I was doing it actually came from the bolt holes to the oil pump on a Stihl. They evidently drilled this one too deep. That was a shocker. Spent a lot of time on that before my friend told me to check that out to, had one happen to him a while back.
     
  19. TJ the Chainsaw Mechanic

    TJ the Chainsaw Mechanic Old Homelites rule!

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    Funny thing is I have had my cs-590 for a few Years and have had no problems with the decomp yet!
     
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  20. CoreyB

    CoreyB Yep I am your neighborhood coffee man

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    Many won't it is just one of those things that are easily overlooked. As a functional design all decompression valves come at a certain risk of problems. Luckily they are usually an easy fix as well as easy to bypass
     
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