USCG Exam PracticeDiesel engine principles (motor propulsion)
In a diesel fuel injection system, what is the consequence of worn, clogged, or dribbling injector nozzles?
- A. Reduced ignition delay, causing combustion to occur before top dead center
- ✓ Misfire, smoke, and overheating due to poor atomizationCorrect
- C. Excessive scavenging air loss through the exhaust ports
- D. Increased compression ratio resulting in mechanical damage to the piston crown
Why B is correct
Injector nozzles have precisely sized spray holes; worn, clogged, or dribbling nozzles degrade atomization, leading to incomplete combustion, smoke, carbon deposits, and overheating. (DOE-HDBK-1018 Vol.1 §1-3)
Cited:DOE-HDBK-1018 Vol.1 §1-3