One of the obvious symptoms of a defective fuel injector is lighting up of the “Check Engine” light in your automobile's dashboard. A bad fuel injector will either deliver more fuel or less fuel to the engine, or fails to operate at the right time. Either of these conditions can lower the engine's efficiency and cause the "Check Engine" light to glow.
Rough Engine Idle:
One of the most common symptoms of faulty fuel injectors is an extremely violent or rough engine idle. If fuel is not properly provided to the engine cylinder, it will result in a choppy engine, when the car is in idle.
Fuel injector can crack or break, which will cause a gas leak. Any cracks on the exterior body of the injector can cause fuel to leak from the body rather than the flowing through the nozzle. If a damaged injector is the cause of the leak, the gasoline will both be visible on the injector and cause a smell. Be sure to check the fuel rails for leaks, as well.
Poor Fuel Economy:
Naturally, if there is a gasoline leak due to a faulty injector, the direct result would be poor fuel economy. A faulty injector may also inject too much gasoline into the engine, wasting gasoline and lowering fuel economy.
Odor and Temperature:
An injector that is stuck open or partially closed will emit an unburnt fuel odor in the engine compartment. A dead injector will cause the engine start and operate when it is cold but not when it is warm.
When too much gasoline is injected into your engine, it causes the engine to surge too fast and then accelerate too slowly. While driving, this will feel like the car will leap up but have a hard time taking off.
A misfiring engine is the effect of the opposite problem – the fuel injector is not injecting enough fuel into the engine. This symptom is caused by clogged injectors, so make sure your injectors are clean. When driving, this will feel like the vehicle is not responding or is delayed when you try to accelerate. This symptom will require an immediate response since a misfire could give rise to engine overheating and pre-igniting the fuel mixture.
A dead fuel injector will cause a non-firing cylinder. Hence, when the engine completes each cycle, it will have a hiccup. This causes the engine to shudder or vibrate.