The red plastic sleeve has a shoulder near the lower end. When it is assembled, the pickup tube is held suspended about 3/8" above the bottom of the tank.
You can see from the glossy red varnish that this screen is barely permeable. When clean, the screen will be a white, woven material. This one would flow enough fuel to idle the car, and even rev it up under load. But, try to go for a drive, and it would still only supply enough fuel to idle. The pump starved for fuel, started to pull a vacuum and heated up until it stalled.
What is probably a dime's worth of parts, deep in the inside of the tank is responsible for having to replace the entire tank. I don't mind replacing a rusted out tank, but it hurts when the tank appears to be in good shape and shows no sign of rot.