how can i fix my vauxhall astra 17cc diseal?

Ihave a problem with my vauxhall astra, when i turn the key i starts up but then it cutts of which is happening all the time, I've chang'd the battery, had a new ecu, check all wires,plugs,ect. Tye'd towing bumping still the same, and i've tryed a memoscanner . has anyone got anymore ideas.plz