Basically that relay should have a constant positive 12 volts at one of it's socket connections , also the ignition should make another socket connection live too,also there is if I recall right a ground connection that goes to one of the socket connections.So if you pop out the relay and check the connectors and none have a positive 12 volts even with the key out, then a fuse or wire is faulty.If you can someone to try and start it while you check these connections another should be live with a positive 12 volts with the ignition in the start position and if not that tell you that the ignition fused 12 volt switchable feed isn't there.
You can peel some spare wire and wrap it around the relays pins one at a time and pop the relay in to test each pin and if the relay is working you'll find another pin will supply 12 volts to the fuel pump.Basically the relay acts much like a switch so if you had the ground pin on the relay grounded to the negative battery post or chassis and you applied a 12 volt positive feed to the relays input pin that connects to the ignition feed , the relay should engage and close the internal circuit and now you should have power coming out of it
Hope that helps and best of luck.By the way by wrapping the spare wire tightly and making sure it's not touching any of the relays other pins you can use a basic 12 volt auto test probe that you can buy from walmarts etc for as little as 8 to 12 bucks or less or buy the big tester and you can use them this way even to test the relay's ground circuit.
Note compare the relays current strengths and probes brightness to a direct battery post test bec it could be a bad wire or faulty ground or bad ground wire etc.Remember that's an old vehicle and if it's all original especially in the fuel pump relay circuit it not hurt to trace the wiring going to the relay and test them all along their full lengths or simply replace them and be sure you clean all the grounds fully and the charging system , starter, alternator, power junctions, engine block grounds etc.
