2004 Ranger XLT 4x4 (4.0 V6) fuel pump/system problem

clutch switch?

The black reservoir/fuel tank selector unit you are referring to is the fuel tank switching valve, which is designed to switch between the two fuel tanks in your 1988 Ford Ranger XLT 4X4. This valve is responsible for directing fuel from the selected tank to the fuel pump and engine.
The second fuel tank selector unit you mentioned (part number 5sv2k) is likely a replacement part for the original fuel tank selector unit. It is not intended to replace the fuel tank switching valve.
The dual fuel tank system in your Ford Ranger requires both the fuel tank switching valve and the fuel tank selector unit to function properly. The fuel tank selector unit allows the driver to switch between the two fuel tanks, while the fuel tank switching valve directs fuel from the selected tank to the fuel pump and engine.
If the black fuel tank switching valve is leaking or malfunctioning, it should be replaced to ensure proper operation of your dual fuel tank system.

codes are OBDll and are available on line free. If some cannot tell what the codes mean do not waste time with them. save this link
https://www.obd-codes.com

https://www.yourmechanic.com/article/p0174-obd-ii-trouble-code-system-too-lean-bank-2-by-blake-griffin

https://www.obd-codes.com/p0174

Fuel pump.

Wrecking yard (or as there called up here, automotive recycling) or dealer is the only place. My question, why the entire line?

first go to an auto partstore and have the code checked. most do it for free. could be coil, fuel pump, fuel filter, air filter or even a bad gas cap. but the dianogstic test should pin point the problem.

your fuse might be loose?

if it is a flex fuel vehicle, it most likely is the flex fuel sensor and/ or connector- it's located on the driver's framerail just behind the door.hope this helps and good luck

drop the fuel tank and check the pump. if you cant, then you can check the wires for the pump.

Sounds like your fuel pump is going out on you. Check your fuel pressure. You should have 40 psi when the key is in "on" position. You should have no less than 5 psi under that when it's running.