Which statement correctly differentiates hot start from hung start?

• A. Hot start involves exhaust temperature exceeding limits; hung start has rpm staying at a low value after light-off.
• B. Hot start involves rpm rising to idle; hung start involves excess exhaust.
• C. Hot start occurs when starter fails; hung start when fuel is cut.
• D. Hot start and hung start are the same.

Answer: (A)

During starting, you distinguish hot start from hung start by how the engine responds: heat vs speed. A hot start means the exhaust gas temperature climbs above safe limits while the engine is starting, signaling overheating or an overly rich mixture that could damage the engine. A hung start means the engine turns over after light-off but does not accelerate to normal idle speed—the RPM stays low and the engine seems to “hang” at the start. So the statement tying hot start to exhaust temperature exceeding limits and distinguishing hung start by the RPM staying at a low value after light-off matches how these start failures are identified in practice. The other choices describe conditions that don’t align with the typical definitions (such as hot start being about RPM rising to idle, or fuel/fuel-cut scenarios) and aren’t accurate distinctions.