looks like i`ve found the problem.mower cut out after only 5 mins use today,did the spark test & has plenty of spark.noticed that the fuel filter was empty again so poured a cap full of petrol down the carby & it started straight away.
went & got 1/2 a meter of fuel line & connected it straight from the tank to the filter.filter filled in about 5 seconds,started first go & ran with no problems while i mowed the back yard.let it sit idling on about 1/2 revs while i did the whipper snipping & it ran until i turned it of,so it ran for about an hour all up.
took the fuel tap off & blew through it,there was definately a restriction in there which i was able to blow out.
so all seems good now,i`m one happy little mower but wondering why it would take so long for the mower to stop with the restriction in the tap ?