2003 Mazda 6 will not start


My son’s mazda 6 will turn over but not start. the things I have done

  1. replace crank sensor
  2. replace cam shaft sensors
  3. it has spark
  4. fuel pump works
  5. sprayed starting fluid in still will not start
    What else should I check?
    Security sytem?


Ran rough just before it quit.
Thermostat stuck closed and engine overheated. replaced thermostat ran good for a day


Do a compression check. Overheated plus aluminum head can mean breached head gasket. It ran good until the compromised head gasket gave way.