I have a cheap Champion mower which has been excellent for the last 8 years,
it has suddenly started to be very difficult to start.

Symptoms
It wont start at all on choke
on slow it fires but peters out before getting going
after about 15 pulls it finally goes and runs fine until I stop to empty the
grass box, then it will be reluctant to restart (although not as bad as when
cold)
On opening the throttle it revs up and down and is reluctant to settle and
it does similar if it suddenly has longer grass.

It seems to be worse if the fuel tank is not more than half full.

What I know its not
Spark plug, changed that it made no difference,
Air filter, took that off and it made no difference
Safety brake not clearing, checked that and it comes on and off as it
should.

Seems like a fuel problem but I have no manual, so is there a fuel filter
somewhere that could be partially blocked?, or could a partial blockage in
the carb produce these symptoms?

Any other low tech suggestions welcome

--
Charlie, Gardening in Cornwall
Holders of National Collections of Clematis viticella
and Lapageria rosea cvs
http://www.roselandhouse.co.uk