In loving memory of Kenis D. Keathley 6/4/81 - 3/27/22 Loving father, husband, brother, friend and firewood hoarder Rest in peace, Dexterday

Saw with a wandering idle

Discussion in 'Chainsaws and Power Equipment' started by dgeesaman, Feb 19, 2015.

  1. dgeesaman

    dgeesaman

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    I am happy with the way my Husky 372XP is running. I think I have it tuned reasonably well, but the idle will slowly wander between 2700rpm and 3300rpm. My other saw idles rock solid. The recommended idle speed is 2700 so it's adjusted to go no lower.

    What might cause this and is it important to fix?
     
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  2. NH_Wood

    NH_Wood

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    Adjustment of low needle help? First thought is small crack in fuel line - does idle change much if you change position of the saw (upright, on side, etc.)? Does the idle surge up and down in a consistent way, or just erratically? Cheers!
     
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  3. dgeesaman

    dgeesaman

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    Adjustment of the low needle did not help. I used the factory manual method of setting the low needle just below maximum engine speed.

    I should hope it's not the fuel lines themselves - I just replaced all of them. But a micro leak is possible I guess. I didn't hold the saw in various positions - I held it the normal way.

    It's not entirely a consistent change in speed - it might run at 2700 for 5 seconds then climb up to 3000, then 3300, then slowly back down to 2700. I can try to post a video this weekend if I get cutting done and the saw is warmed up.

    Once I give it even the slightest throttle the engine is rock solid, load or not.
     
  4. NH_Wood

    NH_Wood

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    Saw wasn't behaving this way at all before replacing the lines? Do any carb work when you replaced the lines (cleaning or kit)? Use any tools which could have damaged the line when you did the replacement? Still leaning toward minor air leak somewhere. Cheers!
     
  5. dgeesaman

    dgeesaman

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    I didn't run it much before tearing it down, as the oiler needed replaced when I bought it. The carb was brand new (and looks it) according to the seller.

    I have a Mityvac - should I drain the tank, tee into the line, and see if it holds vacuum?
     
  6. NH_Wood

    NH_Wood

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    New carb - okay. Yes, test the fuel line if you can. Was the old line bad or did you replace to be safe? Still have the old line? Unless definitely bad, could swap back in and see if it makes a difference. Cheers!
     
  7. dgeesaman

    dgeesaman

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    I might have finally thrown out the old line. I replaced it because I could see some rubbing wear where the rubber passed through the opening into the carb compartment. I will play around with that.
     
  8. NH_Wood

    NH_Wood

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    Let us know what you find - good luck! Cheers!
     
  9. DexterDay

    DexterDay Administrator

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    The fuel line and impulse are a good place to start looking.

    Let us know if that fuel line fixed it.