Common Rail Fuel Injection Systems

• Standard diesel fuel injection systems rely on mechanical pressure generated by the engine. This means that they are not very exact -- the more throttle on the engine, the higher the pressure. This is effective at high RPMs, but when the engine is idling it loses efficiency and spits out more exhaust due to poor diesel pressure. A common rail fuel injection system solves this problem by making the process electronic instead of mechanical.

Separation

• The key to a common rail injection system is the fact that the injection and pressurization are separate processes. The injection system pressurizes the diesel for each firing of the piston in a special chamber; it then releases it as needed.

  This is in opposition to mechanical systems that use a spring to both pressurize and inject at the same time. By separating the processes, the common rail injection system can inject the amount of fuel the engine needs at the pressure level it needs it, rather than just giving it whatever the engine is capable of producing at that moment.

Cars

• One arena where rail injector systems are becoming more common is in consumer-driven cars, rather than commercial-driven trucks. The reason they are becoming popular is because a common rail diesel injection system reduces exhaust and noise -- two factors of diesel engines that tend to turn people off to diesel fuel.

  The reason emissions are reduced is that excess fuel is not burned. Excess fuel, due to inefficient injection, is the reason trucks belch their characteristic black smoke. Making this process more efficient makes a diesel-powered car more attractive to buyers.

Boats

• Boats are another key market for common rail injection systems. The reason for this is that purely mechanical diesel engines are not really designed to idle. Rather, they are designed to be on full throttle all, or at least most, of the time. This is why mechanical injection works for trucks and trains -- they have their throttles wide open pretty much all of the time.

  Boats, on the other hand, specifically fishing boats, need to spend a lot of time sitting in one place. This means the engine needs to idle and when the throttle is re-opened a large amount of black smoke spits out when the excess fuel hits the pistons. By using a common rail injection system, a fishing boat can eliminate this problem.