e36 325i: Injectors not pulsing on start up

[Huz]

Hey there, I have an e36 325i and it now takes a long time to start. once it is started it runs fine, but if i leave it for a few minuets it wont start again. sometimes i will keep cranking it and pumping the throttle and it splutters and eventually starts. most of the time i need to put jumper leads on the battery and eventually it starts. I have taken it to the mechanic and he says that the injectors are not pulsing when its starting. The crank angle sensor has been replaced so its no that the auto electrician seems to think it could be an earthing issue somewhere. any ideas of what the problem could be?

thanks in advance