What Makes Fuel Injectors Flood?

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Even though the fuel-injected engines in most modern cars don't require a driver to pump the throttle before starting the ignition in cold weather, they can still be susceptible to engine flooding.


In cold weather, a car's engine requires a fuel-rich mixture in order to start. However, this can lead to excess gasoline hitting the cylinders, causing the spark plugs to get wet and leaving the spark plugs unable to create the ignition needed to start the motor.


Pressing the accelerator of throttle body injected engines opens the throttle and allows as much air as possible to get into engine, creating a fuel mixture more conducive to cold weather starting. Instead of opening the throttle, pressing the accelerator of a fuel injected vehicle sends a message to its on-board computer system that the engine is flooded. The computer should respond by lowering the mixture of fuel flowing to the engine.


Old spark plugs can cause fuel-injected motors to flood on a regular basis during cold weather starts. Keeping the battery and engine warm with an electric battery blanket or block heater can also help to prevent engine flooding.

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