I have just replaced mine with a Walbro unit. You have to unscrew the bolts off the cover under the rear seat. remove the sender. it has the fuel lines attached. Its tough to pull the sender out of the way to get inside of the tank to pull the pump, but there is a plastic tab that releases the pump from the tank. Pull the pump out. Now there is a harness plug from the sender to the pump and that sometimes goes bad. Remove the pump from the Plastic cradle. be careful, do not break this or you are up the shit creek!! it unclips.
The walbro pump has its own harness and you must splice into the existing harness plug that attaches to the sender. not a big deal. The walbro is much smaller and at first you wonder what the heck. They provide you with a spongee like rubber surround that fits over the walbro. Teh walbro comes with a new filter pick up. be careful when you install this onto the pump. then you place inside the cradle and slip the new pump back into the tank.
That is the option I used. You of course could just buy a factory Bosch pump from nissan at a much more expensive price.