I would agree with the above wiring, though I did mine slightly differently. I reversed 85 and 86. No matter. That's only a switch, in one side and out the other.
I've always found that pictures help. I'll paste a couple in here.
First, the power source. That's the relay on the passenger side fender. I'm taking power with the wire which goes off to the right, with an in-line fuse on it.
I'm controlling the power flow with the switch, activated by the key-on power from the Injector pump. Fir this one, be sure to connect to the forward spade connector.
Both of those wires go to the new relay, wherever you want it to be.
Those two wires, plus the ground on the new relay, take up 3 of the connectors on that new relay. The 4th connector goes to the electric fuel pump, which again must be grounded.