Mountfield 46R PD Lawnmower - Starts but hunts

[EurIng]

have a Mountfield 46R PD petrol lawnmower - two years old.
Engine has started hunting / chugging and won't run at high speed.
I've changed the spark plug - no change.
I've checked air intake - all ok.

Any ideas?

 

[goodmow]

If it has a Briggs and Stratton engine you should change the diaphragm between the carburettor and the fuel tank part no. should be 795083.
If it has a chinese SV150 engine you need to try cleaning the carburettor.
Just also check that the governer springs are ok and the plate hasn't been disturbed.

 

[EurIng]

Spot on - got a new diappragm from Briggs parts & now works ok.

Thanks for the advice.

Regards

 

[goodmow]

I repair garden machinery for a living so it's a good job that i got it right !!!

 

[morrisminor]

My daughter has a mountfield 460PD mountfield mower and she is complaining that it was having running problems, eg the throttle cable does not alter the running speed and is very sluggish. I had a quick look at the spark plug and it was all sooted up as if it had been running on a very rich mixture. I cleaned it up, cleaned out the carb and petrol tank & air filter. fresh petrol and started it up but still the throttle lever does not alter the speed , B4 I started I took a photo of the springs layout on the carb, so that they went back in the same place. Can anyone help me as to why or what is the cause of the leaver not operating as it should. not sure if this should have been put under new topic