How Diesel Fuel Injection Systems Work

By: HowStuffWorks.com Contributors  | 

A diesel fuel injection system differs from a gas engine in that the diesel fuel gets injected directly into the cylinder. In a gas engine, a port injection or a carburetor is used to inject fuel prior to the intake stroke (outside the cylinder) where the fuel mixes with air before it enters the cylinder.

The injector on a diesel engine is its most complex part. The pressure and heat within a cylinder are quite intense and the injector has to be able to handle those conditions while still distributing the fuel in a fine mist. Equally important, the mist needs to be distributed evenly throughout the cylinder. Some diesel engines use induction valves, pre-combustion chambers or another type of device to swirl air through the combustion chamber. This process helps distribute the fuel mist evenly and keeps the ignition and combustion process smooth.

Advertisement

Some diesel engines help the combustion process by using a glow plug, or some other device that helps keep the air temperature in the cylinder at a sufficiently high temperature. If the air temperature is too low, the fuel won't ignite. When the engine isn't running, it obviously gets colder; as a result, a glow plug (which looks like heated coils, like on a toaster) is needed to heat the air when the car is started. By keeping the air temperature high, the engine has a better chance of starting in cold weather.

Originally Published: Jun 16, 2011

Diesel Fuel Injection FAQ

What is diesel fuel injection?
A diesel fuel injection system directly injects diesel fuel into the cylinder. In a gas engine, a port injection or a carburetor is used to inject fuel prior to the intake stroke (outside the cylinder) where the fuel mixes with air before it enters the cylinder.
What is diesel direct injection?
A direction injection diesel fuel system injects fuel right into the combustion chamber at the top of the piston. This type of fuel injection system tends to use higher injection pressure and work more efficiently.
What does an injector do in a diesel engine?
The injector on a diesel engine is its most complex part. The pressure and heat within a cylinder are quite intense and the injector has to be able to handle those conditions while still distributing the fuel in a fine mist.
What are the two basic types of fuel injection systems?
Multiport fuel injection and throttle body fuel injection are the two most common fuel injection systems used in most passenger vehicles today.
Are all diesels fuel injection?
Yes, all diesel engines use a fuel injection system.

Games

Advertisement

Loading...