Hi, some advice needed please. My 3.5Hp has worked perferctly for 10yrs, i come to use it on Sunday and it's fine.
I then refill with petrol and the problems start, i started it and it turns over fine, but it sounds like it is being revved up and down when it idles, you then try and use it and it has virtually no power.
So I've drained the oil and petrol out and will refill with new stuff aswell as putting in a new filter. My question is will this sort it. The only thing I saw was that the idle governor spring(?) seems to be being 'pulled' open and closed in time with the engine revving ast idle.

Oli., May 2010

problem solved, followed Phil Saunders post about looking at the carb....took it apart,full of muck, gave it a clean, runs like new now.....Many thanks Phil!

oli, May 2010

Hi, i've put in new oil, spark plug, petrol, air filter...still no change.....any ideas please??

Oli, May 2010

i have the same engine on a tiller and i changed the spark plug cleaned the gas tank and carb, reset the idle, and the mixture screw and everything seems to be fine

yardman, May 2010

Engine hunting is nearly always fuel starvation( running lean ) if it has a mixture screw try turning it out until it idles steady,if no better check for a fuel blockage in the fuel line or in the carb.

Husqvarna man, May 2010