Just dug through the books for my '98 Blazer, don't know if it's the same as yours though. I would bet it is. Fuel pump relay is in the fuse/relay center. Under the hood, top of left inner fender. Pull cover off and look at the inside of the cover for the relays exact location. 1st, check the 20A "ECM B" fuse to the left of the relay. The fuse provides power for the FP through the relay contacts, pins 87 & 30. There is also a redundant path through the oil pressure sender. Pins 85 & 86 on the relay is the coil. On mine, there is a slot in the plastic housing towards the lower left corner of the relay. Between the relay and the "TRL PRK" fuse. It looks like that is the fuel pump prime connector. There about 6 relays in there that are the same. You might try switching the headlight relay for the FP relay and see what happens. I also sent a scan of that page in my manual to your aol address...
David