LEC Fuel Systems & Injection 3

Question 1

Which type of fuel injector delivers fuel directly into the combustion chamber at very high pressure?

Accepted Answer

Common-rail direct injector

Answer

Common-rail direct injectors spray atomized fuel directly into the cylinder at pressures exceeding 20,000 psi for efficient combustion.

Question 2

What does a high fuel temperature alarm on a locomotive indicate?

Accepted Answer

The fuel cooling system may be malfunctioning

Answer

A high fuel temperature alarm signals that the fuel cooler or heat exchanger may not be removing enough heat, risking vapor lock and injector damage.

Question 3

What effect does a worn injector nozzle tip have on combustion?

Accepted Answer

It causes poor atomization, leading to incomplete combustion and power loss

Answer

A worn nozzle tip enlarges or distorts spray holes, producing large fuel droplets that do not burn completely, reducing efficiency and increasing emissions.

Question 4

When bleeding air from a diesel fuel system after filter replacement, where should the engineer begin?

Accepted Answer

At the primary filter, then the secondary filter, then the injection pump

Answer

Air bleeding proceeds from the low-pressure side (primary filter) toward the high-pressure side (injection pump) to systematically purge all trapped air.

Question 5

Which HAZMAT regulation primarily governs the transport of bulk diesel fuel on railroad property?

Accepted Answer

49 CFR Part 174

Answer

49 CFR Part 174 covers the carriage of hazardous materials by rail, including requirements for handling flammable liquids like diesel fuel.

(LEC) Locomotive Engineer Certification Practice Test

(LEC) Locomotive Engineer Certification Practice Test

LEC Fuel Systems & Injection 3