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Petrol Lawn Mower Hunting

Discussion in 'In the Garden' started by MFRacing, 26 Aug 2018.

  1. MFRacing

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    Hi guys,

    I have this petrol lawnmower:

    https://www.screwfix.com/p/mountfield-hp164-39cm-100cc-hand-propelled-rotary-petrol-lawn-mower/46936

    Had it about 3 months. Yesterday I pulled it out of the shed to cut the grass after not using it for about 6 weeks, and it was a struggle to start but once it did it kept hunting like it was starved of fuel.

    So I tried a number of things to fix it:

    New fresh fuel
    Running it without fuel cap on
    Cleaning the air filter

    None of which made a difference. Still hunting and nearly stalling all the time.

    One thing is if I rev the engine by moving the arm on the side of the engine it revs nice and clean and fast.

    It seems like the system that controls the revs is not working correctly to keep the revs steady.

    Any ideas?

    Thanks
     
  2. HERTSDRAINAGE2010

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    John will be along soon.

    Andy
     
  3. motorbiking

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    Just bend the little arm to make the spring a bit tighter or get an old 3 speed gear lever or brake lever off a bike and make a throttle.
     
  4. MFRacing

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    Cheers but I’d rather fix it probaly than bending anything!
     
  5. motorbiking

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    check the spark plug is clean
    check the springs aren't stuck
    remove the air filter and see if this makes a difference
    give the whole governor mechanisms a good squirt with tf2 or wd40 to make sure its moving freely.
    They can easily get dirt and dust in them and the springs lose their stiffness.
    Check their isn't dirt or grass blocking the exhaust.
     
  6. banjodeano

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    blocked jets in the carburettor?
     
  7. MFRacing

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    Checked spark plug. All good.
    Removing air filter. No difference
    Nothing blocking exhaust.

    Haven’t got any wd40 at moment but will give it a go.

    Thanks
     
  8. Burnerman

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    Are you happy taking the carb off for a clean.....you'll need an aerosol of carb cleaner?
    Its a case of removing the float bowl, and the main jet and emulsion tube inside.
    John :)
     
  9. cwhaley

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    In case you end up looking for a new one, go for a second-hand Atco Admiral 16SE.

    I was given one years ago after I moved out and it's been a workhorse -- it just keeps going and going leaving crisp, bold stripes on the lawn. Others highly rate this model too. They can be found at good prices.
     
  10. wgt52

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    Low Oil?

    (May sound daft but the oil level does seem to affect the pre-set engine speed control)
     
  11. MFRacing

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    Just thought I’d update this. Stripped down the carb and cleaned it all with carb cleaner and compressed air. Back to running sweet as a nut! Thanks all.
     
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  12. Nige F

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    Probably worth giving the fuel a dose of Fuel Fit ( or similar ) to stop it going off over winter. Let it run so the mix gets into the carb.
     
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