Echo Pb-775t bogs down only runs on half choke

Discussion in 'Mechanic and Repair' started by amodedude1, Aug 30, 2012.

  1. amodedude1

    amodedude1 LawnSite Member
    Messages: 3

    Hello everyone, I need your help.

    I spent the whole afternoon trying to fix my blower, It has not been running right for a long time.

    Here are the symptoms:

    1. only runs at a reasonable rpm at HALF CHOKE.

    2. If not at half choke, the engine will bog down and die.

    3. After warming up (for 15-20 min) it needs slightly less choke, but still needs some choke.

    Whats going on? Any suggestions?

    Here is what I did to try to repair the issue:

    1. Replaced all intake gaskets

    2. cleaned carburetor

    3. replaced spark arrestor screen and gaskets.

    4. replaced and gaped spark plug

    5. replaced all fuel lines and the fuel filter

    6. replaced air filter

    The carb has NO adjustments so I was not able to fiddle with anything.

    Today I also noticed that for the past two years I have been using a 40:1 ratio oil. :hammerhead:

    I thought that was what it required and I felt pretty dumb today when I found out it actually uses 50:1 so I swapped out the old fuel also.

    This was all to no avail.

    It is still broke.

  2. Pietro

    Pietro LawnSite Senior Member
    Messages: 855

    Its carbon in the muffler. Take the muffler off and put a torch to it for 10 mins. Let it cool, put it back. Thank the ethanol!
  3. ed2hess

    ed2hess LawnSite Fanatic
    Messages: 14,199

    There is an adjustable jet that is covered with a plug. I think it is straight in from top and uses a d shaped tool to turn. Somebody post about it already but I can'; t find it.
  4. spydahead

    spydahead LawnSite Member
    Messages: 30

    It's to lean,vac leak,or you need to adj that carb.Every echo I own, I've had to adj.the carb because they are all WAY to a search, one screw on the side & one on the top dead center.
  5. ringahding

    ringahding LawnSite Senior Member
    Messages: 611

    What type of fuel have been using? Most problems are due to the use of 87 Octane, we use 91 Octane and no problems....all ECHO.
  6. amodedude1

    amodedude1 LawnSite Member
    Messages: 3

    Hey guys, thanks for the quick reply!

    I am going to do some research on that hidden adjusting screw tonight and see if I can find it tomorrow. I am really leaning towards a carb adjustment and I'm hoping its not anything worse.

    I saw the screw on the side, that one is for adjusting the idle speed. I'll look for a hidden / on the top, adjusting screw.

    I have an exon gas card and one of those speed passes that go on your key chain so 89 Exxon is the only gas I use for all my vehicles and equipment. "Top teir" gas, so it should be good fuel. I'm not sure about weather or not they use ethanol though.

    I'll try the touch trick as a last ditch effort.

    Thanks everyone!
  7. amodedude1

    amodedude1 LawnSite Member
    Messages: 3

    Bad news guys, the adjustment didn't work! :cry:

    I made a tool to adjust the jet by grinding down an Allen key with my dremel.

    The tool worked great and I was able to get things to work just a tad better but its still working like junk.

    The same issue priests.

    It keeps bogging down when I give it gas.

    I'm going to make a last ditch attempt to fix it and replace the crab.

    It that wont do the trick then it must be an air leak from another location.

    Maybe the rings are leaky?

    What do you think?

    (I forgot to mention that I had the jet adjustment turned all the wat counter clockwise in order to get the small improvement)
    Last edited: Sep 4, 2012
  8. ed2hess

    ed2hess LawnSite Fanatic
    Messages: 14,199

    When you take carb apart check to see if the plastic ramp that is part of the needle assembly is okay. I seen one that was cracked and when you pulled the trigger to accelerate it wouldn't pull the needle up. The needle must come up to let in more gas. Or maybe screeen in carb clogged.
  9. sharkey

    sharkey LawnSite Member
    from Pa
    Messages: 50

    Something isnt right. If you raised that needle to the top it would flood. Replace your tank filter and check the lines with a pressure pump for pin holes. The other thing to check is the jelly bean vent check valve. Inside is a small filter, and sometimes it fills up with oil and chokes off the check valve causing it to go lean.

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