Common Rail

Common Rail Specialists

A Common Rail engine is designed to supply constant fuel pressure to electronically controlled injectors though a shared fuel rail. This means the fuel supply is not dependent on the engine revs.

A common rail system is built around four basic components:

  1. A high pressure pump with pressure regulator and inlet metering value.
  2. A rail which contains a pressurised reserve of fuel.
  3. Injectors which inject precise amounts of fuel into the combustion chamber as required.
  4. A Diesel Control Unit – the ‘brain’ of the system, which precisely controls injector flow and timing as well as rail pressure while continuously monitoring the operating conditions of the engine.

Benefits of Common Rail

  1. Accommodates all planned emissions legislation
  2. Opportunity for pre-injection and post-injection
  3. Modular system
  4. Compact
  5. Full electronic control
  6. Fuel Economy
  7. Enhanced reliability and performance
  8. Cover's a variety of vehicle applications

Common Rail testing

Below are two of the many machines we invest in to ensure quality testing of common rail injectors. These machines enable us to test, repair and re-manufacture common rail injectors back to OE specification. See more of our facilities here…
Bosch EPS 708

A fundamental change

Common Rail systems are already fitted to many Ford, Renault, Kia and Hyundai vehicles and many new applications are planned for the near future.

Delphi has been involved in the development of Common Rail technology from the beginning. Some of the first systems were pioneered by Lucas Diesel Systems and Delphi has inherited this expertise.

Common Rail marks a fundamental change in diesel technology and is happening now.

More and more vehicles are being introduced with Common Rail systems. It is calculated that 70% of new diesel vehicles will incorporate Common Rail injection systems and 5 million such systems will already be on the road.


  • The common rail system creates atomised ultra-high pressure fuel.
  • The nozzle pressures range from 300 bar (4351 psi) to 2200 bar (31908 psi) depending on the vehicle and system.
  • This can lead to potential serious injury if the system is worked upon by untrained personnel.
  • If you have any questions regarding problems please contact one of our fully trained staff.
  • Correct diagnostic, testing and cleaning equipment is essential to safely work on Diesel system.

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