Good work
I would unplug the computers connector and check inside for corrosion, also check ground wires around the computer, make sure they are tight
Also do as PJ412 said and get him a picture of computer label
pin 22 on the computer should be a GROUND on boot up and then no ground until engine starts, then its a ground again
So ground for computer is important, and good wire connection
That's what turns on the FP Relay
You can operate vehicle with jumper on the OBD1 connector in place, yes there is a safety concern because computer would shut off FP relay when engine stalled in an accident, but really up to you
Its not harmful to the electronics just a possible fire hazard