Delphi Smart Injectors and Electronic Unit Pumps

How Delphi Smart Diesel Fuel Injection Technology Works

The Delphi smart injector for medium to heavy duty diesel engines is a high pressure, electronically-controlled diesel fuel injector that is designed to be combined with the Delphi electronic unit pump (EUP). This combination provides a complete high pressure fuel delivery system for “cam in block” engines or engines with separate cam boxes.

Currently, only Delphi combines an electronic unit pump with an electronically-controlled smart injector for DAF engine applications. The injector’s nozzle control valve is electronically-controlled, which helps to reduce fuel consumption and improve performance, all while meeting the most stringent emissions regulations.

When paired with a smart injector, the precise start of injection can be further adjusted by the injector control circuit. Delphi’s EUP’s use proven valve technology from Delphi’s EUI product line. When used in conjunction with the high pressure electronically-controlled smart injector, the EUP provides a complete high-pressure fuel delivery system for heavy duty engines.

The EUP (electronic unit pump) operates in the following manner:

  • Filling plunger descending, valve open
  • Pre-spill plunger rising, valve open
  • Pumping plunger rising, valve closed
  • Spill plunger rising, valve open – refer to diagram below


The pumping mechanism is identical to an inline or single cylinder pump. The plunger – which is driven by the camshaft – moves up and down in the body. Pressurised fuel moves freely from the engine fuel manifold, through the pump, and back into the manifold.

At a certain point during the pressure stroke, current is supplied to the actuator. This current generates a magnetic field within the actuator and causes the high-pressure valve to close.

Once this valve is closed, fuel cannot exit the unit back into the engine fuel manifold. The action of the plunger upon the fuel creates very high pressure.


Due to the precise operation of both the EUP and smart injectors, specialised Delphi tooling and test equipment is required to be able to repair, test and calibrate EUP and smart injectors.

Cornells, an authorised Delphi repairer, has all the tooling and equipment required to offer customers testing, overhaul and new replacement EUP and smart injectors. For more information please contact us on +61 3 9267 8800