immobiliser w reg 2.5 tdi minibus swb nana engine?

just change fuel tank as it got screw driverd started van it ran a few yards then died now it wont stat. it tries to fire but wont is there a fuel cut off switch i have fuel to the injectors could it be the immobiliser as the light is acting different to wot it used to to. could it be my key red chip in it any ideas ????????? thanks