Fuel pumps die in two ways: gradually over months (intermittent symptoms, then permanent failure) or suddenly (engine stops while driving). The gradual mode is much more common and lets you replace the pump on your terms.
Warning signs: a high-pitched whining noise from the rear of the vehicle when the key is in 'on' position (the fuel pump is supposed to be quieter than the engine), hard starting when the tank is below half, engine sputtering or hesitation at sustained highway speeds, sudden stalls during hot-weather driving that restart after cooling.
Driving consistently below a quarter tank shortens fuel pump life. The pump is cooled by surrounding fuel; less fuel means less cooling means faster wear.
Replacement cost runs $300–$800 at a shop. The pump itself is often $100–$200; labor is the bulk of the cost because the pump is inside the fuel tank.
If you suspect fuel pump issues, get the pressure tested at a shop ($30–$60). The test is conclusive and tells you whether replacement is needed.