I have owned my BMW E36 323 (2.5) since December and never had a problem with until today , i can turn the ignition on everything lights up radio comes on all exterior lights work but there is nothing at all happening when i try to start it you can here a hiss which i presume is something to do with the fuel pump , i had the RAC out who bye passed something and had the starter motor working but it wouldnt start he seems to think the immobiliser has kicked in .... BUT i didn't know it had one i have 3 keys a grey one a black one and a plastic one but none of them will start he car