Which of the following conditions may cause...

🔍 Key Concepts

• Diesel engine runaway/overspeed on startup and what uncontrolled fuel sources can cause it • How faulty fuel system components (like injectors) affect engine speed and fuel delivery • How external or unintended fuel sources (e.g., lube oil past turbo seals, airborne hydrocarbons) can enter the intake and act as fuel

💭 Think About

• Think about what an engine actually needs in excess to overspeed on startup: is it air, fuel, or load that changes the most suddenly? • For each option, ask: could this condition provide extra, uncontrolled fuel or fuel-like vapor to the engine right when it starts? • Consider whether any of the listed conditions could independently cause overspeed, and whether some of them describe similar underlying problems.

✅ Before You Answer

• For each choice, decide if it can realistically lead to uncontrolled additional fuel entering cylinders at startup. • Ask whether turbocharger seal ring failure can let lube oil or fuel into the intake side, and whether that can burn like fuel. • Consider if airborne hydrocarbons in the engine room air could be drawn into the intake and act as fuel during startup.

Which of the following conditions may cause an engine to over speed on initial startup?

Faulty injectors

Turbocharger seal ring failure

Airborne hydrocarbons in surrounding area

All of the above

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🔍 Key Concepts

💭 Think About

✅ Before You Answer