service engine light came on, go a whining noise that sounds like a fuel pump, how easy is this bad boy to change out?

I had mine replaced by the dealer under warranty. If your truck is still under warranty get it done for free.

X2, Mine's been bad for the past 6 months or so. I've got a laundry list of stuff for my dealer to look at so I'm going to do it all at once (once I replace the clutch)

yeah, as do I. New tires, fuel sending unit, inspection, tranny flush, diff flushes, transfer case flush, radiator flush, big time bucks at the dealer! hahaha CRAP!

there was a recall on that for a lot of 2nd gens

My check engine light just popped last night! I was camping in NH last week and I filled up my X and it didnt show filled for a at least an hour. Same thing happend yesterday and then BAM check engine light. Oh well, it is covered under warranty until 72,000 miles or 6 years. Nissan should send you something on the extention of warranty if this happens to anyone else. The X needed a few more things fixed anyways, stupid heat shield!

I have an 2002 Xterra and im not sure but it might be the same parts... Honestly it took less than a hour and there is an access plate below the rear seats where you remove and replace the fuel sending unit. It was very easy to do. Just be careful disconnecting the fuel lines they are under pressure and may spray everywhere inside your truck (like it did mine) then you are just left with the smell of gas for a week...

If you need more info let me know.

Yea, if you have a 1st gen it's easy. For those of us with 2nd gen Xterras, it's a little more involved but totally doable for about $80 or so ($400 if you have a dealer do it out of warranty).

If you wanna save some money and have a little fun, here's a DIY I wrote up on ClubXterra.org

It's easy to change the fsu as it involves dropping the tank. Fuel pump is kind of attached with it. Just replace them both. Make sure tank is as empty as possible as it is awkward to do unassisted. Took me 3 hours.