Black Smoke

Black smoke is caused by too much fuel being processed inside your car's engine and then released from the tailpipe of your car. Malfunctions in fuel delivery or internal system leaks will cause black smoke to come from the tailpipe. Before fuel injection became available in automobiles in the mid 1980's, the carburetor was the main fuel and air mixer in most vehicles. A carburetor was a simple device that supplied the engine with proper fuel to air mixtures. Carburetors performed two operations 1. meter air flow 2. deliver the correct amount of fuel to air mixture. This mix could be kept even during the wide range of extra factors associated with an engine such as high temperature, cold starting, hot starting, idling and acceleration.

The primary difference between a carburetor and a fuel injection system is that the fuel injection system atomizes fuel by pushing it through a small nozzle under pressure, while a carburetor utilizes vacuum created by air flow into the intake manifold. Airflow in an injection engine is controlled by the throttle body; fuel is distributed directly in each cylinder. This creates better fuel control, lower emissions and faster acceleration. The process of measuring the amount of fuel a fuel injector is dispersing is determined by the ECM (engine control module). The fuel injection system has several parts: the mass airflow sensor or map sensor, throttle body, throttle position sensor, idle control valve, fuel pump, fuel pressure regulator, fuel lines, and oxygen sensors.

Cause of Black Smoke

Black smoke is caused when the mix of fuel and air becomes un-balanced. Normal mixture is 14.5 parts air to1 part fuel. When the fuel to air mixtures change because of a malfunction the mixture can go as high as 14.5 to 2 or 3, two to three times the proper amount. The black smoke is the excess fuel generated from the rich mixture and can be cause by one of the following:

Plugged Air Filter

Shorted or stuck fuel injector

Failed fuel pressure regulator

Vacuum leak

Shorted ECM Sensor