1981 - ECM problem, fuel pump problem

[Adrian12]

hi!

I've a 81 deville V8-6-4 6l and the following problem!

from one day to the other my fuel pump doesn't work on turning ignition on and at trying to start. but from the same time my ECM doesn't want to go in diagnostics mode.
If i press "off" and "warmer" ".." appears but not "88".

what could I do now? i think the fuel pump is okay, but the ECM has something that the fuel pump doesn't work.
Sometimes the diagnostic mode works, but after short trying to start its the same problem again!

pleas help me!

thanks