my mower starts but wont run?

If you mean that it starts up then will only idle, you may just have to check that the throttle cabe is working on the carb end when you operate it.
If it is, it may just want adjusting so when it`s not running, slacken or take off the cable anchor on the carb end and pull the cable away from the carb so that when you operate the revs, it pulls the linkage more and revs up.
It`s worth a go.
If the engine is reving up and down then it may also be the carb linkage/springs.

jimmy.
July 2009

check sparkplug or replace make sure petrol is not contaminated or old flush out petrol and replace with new if this does not work and your mower is old it may not be worth taking it to a repair shop

derek
July 2009