320i L-Jetronic won't start

[DarioStraightSix]

Last sunday,after two weeks of inactivity i wanted to take my E30 for a ride but...surprise,it won't start. I checked spark plugs,cables and the rotor. Everything ok. Then i noticed a thing,once you turn the key you don't listen the fuel pump. So i thought "fuel pump is gone". At this point i ordered one,it arrived friday i installed it but nothing. My E30 still don't want to start. After some internet research i discovered that there's a relay that "drives" the fuel pump. I checked it but it seems ok and you can clearly listen its "click" when you turn the key.
In my opinion the problem is that the 12v don't reach the fuel pump but i don't understand why. I checked it with the key turned and at the + and - of the fuel pump the multimeter signed 0 volts

Have you got any idea?
Thank you in advance!

EDIT : it's an '84 320i with L-Jetronic injection and external fuel pump.

[Brianmoooore]

Fuel pumps only run when the engine is turning.
The signal to activate the fuel pump relay is usually obtained by integrating the pulses that eventually provide the sparks for the plugs, so the first thing you should be checking is whether you have sparks at the plugs.

[DarioStraightSix]

Thanks for your help guys!!!

Anyway it's alive!!!!! The problem was the wiring connections where the pump relay is mounted. Had been modified for the shitty methane system. I did a tidy up at everything and the old M20 started at the first turn!
Probably the old pump was still ok but i think that a new fuel pump on a 30+ years old car is not a bad idea. The new one is quieter and i felt the car smoother when flooring during the little ride i did this morning.