You could have a break in one (or more) of the copper traces on the backside of the board.
Or a problem with one of the wires coming into relay board via the 14 pin connector.
Sounds like you've ruled out the relays.
How do you know if your replacement relays are any good?
Did you pull one from a headlight motor that you know is working?
See attached diagram.
When you turn the key, you should get power at pin 86...and better have power at pin 30 as well.
A functioning relay will send the power from pin 30 out pin 87 to your fuel pump.
Some things you can check.
1) You should always have continuity from pin 87 to your fuel pump.
If not, there is something wrong with either the trace on the backside of the board from pin 87 to the 14 pin connector (possible) or a problem with the wire from the 14 pin connector to the fuel pump (unlikely).
2) You might not be getting power to pin 86.
Either a problem again with a broken trace on the backside of the board from pin 86 to the 14 pin connector or a problem from the 14 pin connector back to your ignition switch, the black wire.
Again with the key in the run position, you better have power at both pin 86 and pin 30 in the fuel relay socket.
If you do, you can narrow it down to either still a bad relay or a problem with the current path to the fuel pump (either a trace on the backside of the relay board or the wiring from the 14 pin connector to the fuel pump).
Click to view attachment