Fuel delivery problem..

Are you sure that it's not the relay, itself, that's defective? Wiring doesn't usually just go bad on its own - something usually has to pinch it, short it out, burn it, melt it, or otherwise cause some extreme damage to it to make that a primary issue (which is usually a matter of something else being catastrophically wrong).

Are you checking to see if power is getting TO the relay from upstream, or are you checking it immediately AFTER the relay? If you're not getting power TO the relay, then you're going to have to manually trace the wire all the way back to the next link in the food chain and verify that there are no faults in the wire insulation, burn-throughs, kinks, pinched points, shorts, corrosion, or other physical damages. If you're not getting power FROM the relay, either find a non-essential relay of the same type on the vehicle that you can borrow (like the A/C system, for example) that you KNOW is functional, and see if that changes anything. There are also ways to check the relay, itself, with a mutlimeter, but I'm not quite in the know of that sort of electronic wizardry...

Lastly, if it comes down to it, just spend a couple of bucks on a small roll of wire of a sufficient gauge (I'm guessing something like 14 to 16 gauge is what's being used), and run a fresh wire from the power source to the relay. SOLDER the connections if you splice it in - DO NOT use those crappy crimp connectors. If you still can't get power to the relay, then move farther upstream until you get to a point where you do have power, and work your way back down towards the relay and then the pump, again.