200 merc efi start no run

[mn808gade]

2001 merc 200 efi, had antisiphon valve plugged-fixed.cleaned all supply lines,new primer bulb,lift pump diaphram kit,new spin on filter on motor.no voltage to hi press pump at negative term(fuel pump driver out) corrected by installing relay fired from purple wire(with key on).now have 35#+ pressure at shrader valve with key on.key off pressure drops to 30# and stays there for hours. turn key- starts and runs for 2 to 4 seconds and dies.fuel pressure stays 35#+.starts over and over but will not stay running. all help will be appreaciated-th