2760. During main engine performance testing it is noticed that the firing pressure in one cylinder is lower than the average, but cylinder compression pressure and fuel pump delivery rate are normal. Which of the following would most likely be the cause?

Late fuel injection initiates combustion later in the power stroke, reducing firing pressure while maintaining normal compression pressure and fuel delivery. This contrasts with worn piston rings, which would lower both compression and firing pressure, and early fuel injection, which typically increases firing pressure. Normal engine load affects all cylinders, not just one, and compression pressure is unaffected by load. Therefore, late fuel injection is the most likely cause of the observed symptom.