Fuel Systems & Injection Flashcards

What is the primary purpose of the fuel injection pump on a diesel locomotive?

Answer: To meter and pressurize fuel for delivery to injectors

The fuel injection pump meters precise amounts of fuel and raises it to the high pressure needed for atomization in the cylinders.

What condition is indicated when a locomotive's exhaust appears black and sooty during operation?

Answer: Rich fuel mixture with incomplete combustion

Black exhaust indicates a rich mixture where excess fuel is not fully burned, often caused by clogged injectors, restricted air intake, or over-fueling.

Which component in the fuel system prevents air from entering the injection lines?

Answer: The check valve

Check valves maintain line pressure and prevent air ingestion by allowing fuel flow in only one direction.

When must a locomotive engineer report a fuel oil leak discovered during pre-trip inspection?

Answer: Immediately before moving the locomotive

Any fuel oil leak must be reported immediately before the locomotive is moved, as fuel leaks create fire and environmental hazards.

What happens to diesel fuel viscosity as fuel temperature increases?

Answer: Viscosity decreases, improving atomization

Higher fuel temperature lowers viscosity, which improves atomization through the injector nozzle but can reduce lubricity.

A locomotive's fuel system develops a vapor lock. What is the most likely cause?

Answer: Fuel temperature is too high, causing fuel to vaporize in lines

Vapor lock occurs when fuel overheats and vaporizes in the supply lines, interrupting liquid fuel flow to the injection pump.

What is the function of the injector return line (spill line) in a diesel fuel system?

Answer: It returns excess pressurized fuel from injectors back to the tank or cooler

Injector return lines carry unused high-pressure fuel back to the tank or a cooler, maintaining proper injector temperature and system pressure.