Nowaday the common rail system become more and more popular in market, main systems include Bosch common rail system, Denso system, Delphi system, Cummins system etc.But many people don’t know how to tell the EUI, EUP and common rail injector, thought they are all electronic injection common rail injector, so let’s see the detail as below:

Firstly let’s the differece of the appearance:

EUI= Electronic Unit Injectors
Volvo eui delphi eui

Caterpillar engine injector

EUP= Electronic Unit Pumps

EUP injector Bosch Electronic Unit pump








Common rail injector 


Secondly, let’s see the difference in their system.

There is no common rail in EUI system, the injection pump and injector are been connected together.


EUI System injector

There is also no common rail in EUP system,  The ECU(Electronic Control Unit) control the unit pump directly.

diesel engine unit pump

There is a common rail in the common rail system that connect the injectors, the ECU controls the common rail injectors to work.

common rail system

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