Scag freedom z stalls out after about 45min of use

[Brendon2010]

My scag freedom z 19hp kawasaki start stalling after 40 to an hour of use,and sometimes there's not much gas if any in filter window. And other times there's some. What can be causing this

 

[BlazNT]

Check for dirt and crud in the fuel tank and fuel lines. Change the fuel filter.