99 citoren berlingo 1.9d wont start think its immobilser ?

my berlingo van has been sitting for a while with no battery i am trying to start it and i dont think the fuel pump is coming on i beleive the problem is in the immobiliser it is the chip in key one btw.......i am wondering can i bypass it and does anyone know if i can run a switch from the fuel pump to the battery and just hit the switch before starting or do i just need a new ecu and chip from the scrappys?
i would love to know if i can just run a switch to the pump or if there is anotherway of bypassing it ie using the keypad out of some other model or could i just change the ecu and the key barrel plus the transponder chip please help i have had no van for months and dont have money for a mechanic.. if anyone would rather email me thanks