In an older diesel fuel system, which component feeds fuel from the tank to the engine?

• A. Injection pump
• B. Lift pump
• C. High-pressure fuel rail
• D. Return line

Answer: (B)

In an older diesel system, the lift pump is responsible for delivering fuel from the tank to the engine. It provides a steady, low-pressure supply to the injection pump, ensuring the injection pump has fuel to work with and that the engine can start reliably. The injection pump then builds the high pressure needed to push fuel to the injectors. The high‑pressure fuel rail and return line aren’t the feed path in these older setups—the fuel rail is a feature of newer common-rail systems, and the return line simply sends excess fuel back to the tank. So the lift pump’s job is to move fuel from the tank into the engine’s fuel system, supplying the injection pump.