Directly wire your fuel pump to your battery and control it with a toggle switch mounted into your plastic. Seems to work well for Tony aka Swamp'Dale.
If the fried circuit got other things you will still need a new ECU, but this will prevent it from happening again.
I would also test that relay you got from Napa to be sure it has a diode in it.I would hate to have you fry your new ECU.And I really wouldnt trust the guys at the counter.
I dont think the relays have a diode in them . I think they use a resistor. On the side of most relays they usually have a wiring scematic which shows a zigzag line on them next to the coil .They are made to absorb a voltage spike.
My stock relay on my 03 Cannibal has the diode in it on the schematic. There is a diode symbol which is a triangle with a line on top. Resisotrs will not help voltage spikes, there are not made for that. The slanted lines you are seeing maybee the coil symbol, which does act like a resistor in a way.