[Stealthee]

Lesson one you learned already, never do business with family.

Now, while I don't have extensive knowledge of wiring diagrams and relays on a 98 Sentra, I can tell you what I did on my Stealth. I had to run a new wire from my MFI (basically fuel pump relay) to my fuel pump. When I did it I put a switch inline before the pump so if I wanted to disable the pump I could do so.

So basically if I flip the switch someone can put a key in and the car will crank, but it wont run due to no fuel unless they found the switch.