The fuel pump relay, on my '85, is located in the fuse box.
The relay itself, looks like a 1/2 pack of cigarettes.
It is sealed, but you can easily open it.
At the male pin end, you'll find 2 solenoids.
The small one is overspeed.
The larger is what you want. Roll the unit over, and check the solder joints on the solenoid supports. These are the grounds to the circuit. If you can gently wiggle the support, you'll see the broken solder joint. I think the factory did a "cold solder". Anyway, solder it. Be careful not to over heat the circuit board.
Good Luck, John F.