Does anyone know where the fuel pump assembly lives? I've got a replacement fuel filter to drop into the Whale but I'm buggered if I know where the assembly lives. New Zealand has pretty rubbish fuel so filter replacements every 40,000 miles is a bit of a must

 

It is located under the rear driver-side (US Model) seat cushion.

 

As rkw stated, It's below the rear seat, driver side. check the below thread for pics.
https://www.clublexus.com/forums/ls-3rd-gen-2001-2006/445122-how-to-remove-rear-seats-01-03-ul.html

Caution: After removing the triangle shaped cover (with 3 nuts) be ready with lots of paper towels while removing the pump, cuz the pressure inside will make it sprinkle fuel all over the place. ( Don't ask me how did I know )

 

If you remove it, take a light and shine it towards the bottom of the tank and let us know if you see any sediment. American fuel is pretty clean these days and it filtered several times before it is dispensed at the tank. Still, I'm sure debris has a way of getting into the tank.

 

I too, would be curious on the condition of the tank bottom. HOWEVER, I would be very VERY cautious and careful with using a light. I absolutely would NOT use a traditional 120vac "droplight" with an incandescent bulb. Personally, I wouldn't use a plug-in type drop light at all.

Use a AA Maglight (LED style, not xenon) or similar battery style flashlight. I would also turn the flashlight on OUTSIDE of the car, not inside the car. Before doing any of this work, I'd also roll down ALL the windows to prevent any gas vapors from building and exploding by some sort of 'invisible' spark (likely from a 120vac switch with a heavy load 60w or 100w lightbulb).

I'm very very VERY paranoid when dealing with gasoline, especially opening a gasoline canister or similar while INSIDE an enclosed vessel (a car). Spend a couple extra minutes to do it the careful way----so you can comeback to update your findings this thread!

PS---I've been contemplating replacing the fuel filter also, but am torn with letting dealer do it (out of my gasoline paranoia) or doing myself to save the $$$. Ironically, I'll always leave the car running when fueling up, even though all gas station signs & owner's manual say to shut engine off. Figure that one out, lol.
PPS---When taking gas cans for yard equipment to get filled up, I get the cold sweats, lol. I always debate with myself... place the gas cans in the trunk or the car and roll down windows? There, now you guys know one of my deep dark secrets.....petrified of gas vapors in enclosed areas!

 

I haven't seen anyone use an incandescent work light in a long time. I should be more paranoid than you considering our power is 240V at 10A. I've got 5v, 12v and 18v LED work lamps so I'm well covered there. I have done work around a fuel tank before so I know the risks when it comes to that sort of thing. I can guarantee the bottom of my fuel tank will be full of schmoo because NZ fuel is pretty average. Even our 98 octane is still rubbish. I can't seem to access the link Mhussein posted though.