Lawn mower coughing and spluttering

[YorkieJohn]

My petrol lawn mower seems to be struggling as if it is not quite running right ,coughing and spluttering a bit ,anyone got any ideas what it could be. Starts after about five pulls. The lawn mower is a Mountfield Delta with a Briggs and Stratton engine. I have no manual as it was bought second hand so any advice would be welcome.

[beechgrove51]

If it is last years petrol,then this can become stale and lawnmower will not run smoothly.Also,check air filter does not require cleaning.Sounds as though it really needs a service.

[Brooksy]

Old petrol`s favourite as beechgrove says, I know, it stuffed my Mountfield `til I drained it & refilled.

[catmando]

I topped mine up with diesel by mistake. It coughed and spluttered until, after realising what I'd done, I drained it and re-filled with fresh petrol - problem solved.

[nonomaybe]

If you haven't already done so start the season with a new spark plug, the b&s engines are probably the best(I always look for machines with b&s engines) so there won't be much wrong with it!!