Which of the following describes common symptoms of a faulty or leaking injector?

• A. Smooth idle and no leaks.
• B. Reduced fuel temperature.
• C. Rough idle, misfires, reduced power, poor acceleration, fuel odor, and possible leakage.
• D. Increased power.

Answer: (C)

When an injector isn’t delivering fuel properly or is leaking, the engine can’t maintain a clean, balanced air–fuel mixture. That mismatch shows up as rough idle and misfires because the affected cylinder isn’t firing correctly. The engine also loses power and acceleration as combustion becomes inconsistent or overly rich, so you feel reduced performance. If fuel is leaking, you’ll often notice a fuel odor and the potential for visible leakage, since fuel is escaping from the injector area. In short, these symptoms together point to a problem with fuel delivery from the injector. Smooth idle with no leaks would indicate the injector is functioning, reduced fuel temperature isn’t a typical sign, and increased power would not come from a fault.