Question 475Motor Plants - Assistant Engineer

The correct answer is C) low starting air pressure. When a diesel engine is started using compressed air (known as "starting air"), low starting air pressure can cause the engine to turn over slowly without firing. This is because the starting air needs to be at a sufficient pressure to adequately compress the air-fuel mixture in the cylinders and allow the engine to start. If the starting air pressure is too low, the compression in the cylinders will be insufficient, preventing the engine from firing properly. The other options are incorrect because they do not directly relate to the issue of starting air pressure. An obstruction in a cylinder (A) or water accumulation (B) would not specifically cause the slow turnover observed, and low scavenge air pressure (D) is a different system from the starting air.