And China can fit these fighters with China made more superior engines; so why need AL-31?
first of all China have many spare AL-31F engines.
all current fighter jets have using Chinese made WS-10 family engines include new J-15T variant as well. only J-15 base variant have AL-31F engines but i m sure new batches equipped with WS-10 engine. Shenyang also re-engined many J-11 with domestic ones. coz China completely shifted to domestically produced machines so no solid reason to use AL-31 engine anymore, since you need to do extra work for spare parts and maintenance.
when AL-31F engine will complete its life cycle on old J-15, Shenyang will switch to WS-10 automatically.