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Fuel coming from impulse line?

Discussion in 'Chainsaw' started by MaddBomber, Feb 14, 2020.

  1. MaddBomber

    MaddBomber ArboristSite Operative

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    My MS260 has been getting extremely flooded at start up and is impossible to start using all the tricks I've learned.
    There's fuel mix coming out of everything; muffler, decomp, and carb. Spraying(!) out after only one pull.
    One day I got her running on the first pull and she ran like nothing was wrong, though I did notice the L was too rich as she'd bog if layed on her side. Tuned her and ran her for a few hours limbing a few oaks. Thought my troubles were over.
    That night, I couldn't get it started... Flooded like crazy and I never even engaged the choke at all.
    I ended up turning the L all the way in. Seated. Closed. Still flooding badly with fuel pouring out of the muffler and carb.
    Today, I pulled the carb and decided to try and clear out the bottom end, so I removed the plug and pulled her over a few times. Gas spraying out of the impulse line. Lots of it with each pull.
    I thought the impulse was for pressure/vacuum to manipulate the carb's diaphragm and act as a pump...
    Is fuel supposed to be coming out of the impulse? I've pulled it about 60 times with no carb, and still fuel continues to come out of the impulse.
    Huh?!?! So confused as to how the gas is getting there.
    Never replaced, removed or messed with either line.
     
  2. Mad Professor

    Mad Professor Addicted to ArboristSite

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    I suspect a problem with the metering needle/seat. Either crud and/or needs a new needle.

    Could check by pressurizing fuel line to see if it holds pressure.
     
    trains, Duce and s sidewall like this.
  3. MaddBomber

    MaddBomber ArboristSite Operative

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    I figured crud. Saw does have a lot of hours.
    Ordered a rebuild, but I'll definitely try to pressure test the carb once it's rebuilt. Luckily I've got a parts 026 with a walbro 194, not this 826 thing.
    Thanks. It's a real head scratcher.
     
  4. cuinrearview

    cuinrearview Red saw lover

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    If it flooded to an extreme fuel in the crank case could pump out the impulse line.
     
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  5. s sidewall

    s sidewall Addicted to ArboristSite

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    I second that motion on all the fuel in the crankcase, it's got to go somewhere when the piston comes down.

    Steve Sidwell
     
    Duce likes this.
  6. PV Hiker

    PV Hiker ArboristSite Operative

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    Also possible torn diaphragm. The piston sucking gas straight from impulse line?
     
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  7. MaddBomber

    MaddBomber ArboristSite Operative

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    Just pulled apart the carb. After the diaphragm dried it was thick feeling and extremely stiff. Wrinkled up like leather. Thinking I've found the culprit.
    The first 100 (or so) tanks of fuel were E-85 as I didn't have any other options. Now that I'm in NC, I can get ethanol free at the pump.... so I should be good.
    Thanks for the input. I've had fouled carbs plenty of times, but never seen fuel squirting out of an impulse line. I'm kinda amazed that it ran a few days ago.
     
  8. Snowchaser

    Snowchaser ArboristSite Operative

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    My dads saw sat for years and when i went through it, the gas had drained into the crank case and then evaporated leaving quite a bit of 2 stroke oil there. Had oil dribbling out the impulse line. Tipped the saw on end with the carb off and the piston up for a few days to drain it. Poured a little mix in and slosh it around and drain it again. Smoked like hell for a little while after it finally started.
     

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