The 5 terminal relays are standard now and are fine to use for replacements, if they fit into the older base/socket.
here are the power paths for the fuel pump system:
battery----------fuse(fusible link)---------fuel pump relay-----inertia switch------fuel pump-----ground
Above is fuel pump power, now relay power:
Battery-----EEC relay------fuel pump relay--------computer(PCM)-------ground
Here is a diagram of a standard automotive relay:
Free ASE Study Guides: Automotive Relays
connections 85 and 86 will close(activate/on) the relay when power is passing thru, in the Ford system(and most others) connection 85 will have 12volts when key is on, but connection 86 will not be grounded so there will be no power passing thru.
These can be reversed, there is no direction requirement for power passing thru the relays "coil".
85 or 86 should show 12volts when key is on, that means EEC relay is sending power to this relays "coil"
30 and 87 are the LOAD connections for the relay, this is where the high amp voltage for the Fuel Pump passes thru when relay is closed(activated/on).
87a is that 5th connector, it can be used to pass power when relay is open(off).
30 will be connected to the battery/fuse and have power all the time
87 will be connected to the inertia switch/fuel pump
These can also be reversed in this application since 87a is not being used.
It reads like you have voltage at all the correct places, but computer(PCM) is not grounding the relays coil(86) when it should.
I would test the voltages just to be sure.
The Light Blue/Orange Stripe wire coming out of the relay base is the "ground" wire that runs to pin 22 on the computer.
The computer has a few Ground wires around it that need to have good clean connections so it can use them to ground things like the fuel pump relay and fuel injectors.