Fuel pump for a 1999 pontiac bonneville will not start after replacing it

Check the fuse for the pump first. You can check that fuse for power when key is on with a test light. Then find the fuel pump relay, probably in relay box under hood, and put your finger lightly on it and listen and feel for it to click when someone turns the key to on.
If relay does click, the problem is likely with the wire to tank from relay, the connector at the tank, or the wire going into the pump.
If relay doesn't click, or if it does and you haven't found problem yet, pull the relay out and with test light grounded to engine, probe all relay terminals for one hot terminal- one will be hot at all times. If no hot terminal, could be fuse link or maxi-fuse that feeds that relay box. If one terminal is hot, have someone be cranking the engine over while you check the other terminals for a second hot terminal. When cranking, two terminals should show power, the main feed for pump, and the signal from computer that energizes relay so power is passed to pump. If two terminals are hot when cranking, try a known good relay. If still no help, problem is with wiring to the pump from relay, or the ground for that relay needs checked.
Post back with what you find. Good luck.