Pontiac Problems? Ask a Mechanic for Answers ASAP
Have you got the fuel tank out?
Can you see the connector with four wires on the MRA (top of the fuel pump assembly)?
Ok, Grey is pump positive, Black is pump negative (ground), Purple is sender positive, Brown or maybe brown/yellow is sender negative (ground).
You only need the Grey and Black for your pump upgrade.
If you feel the factory wiring might not be up to the task, you can use the grey wire to operate another relay.
Then run a new positive feed (and ground lead if you like) from your battery through the rear firewall.
I hope this helps you.
I hope my advice has been of assistance to you.