406 hdi 90 non starter

Hi Can any one shed some light on this one, car will not start off the key will only start when easy start sprayed in, runs fine then will cut out when pushed hard and at same time message comes up air pollution fault, only way to get it running again is use east start, so far we have put new pump in tank, new crank sensor also no faults on snap on scan tool plus we have ecu checked, also noted was infrequent pulse at injectors when cranking. regards jim34