New Holland 667TA/EBF, Repair Manual

Page: 68 / 150

2-50
Issued 11-06 Bur 87519804 NA
CHAPTER 2 - 667TA ENGINE OVERHAUL
ENGINE REPAIR MANUAL
When the pumping element chamber pressure
becomes less than the supply pressure, the intake
valve is again opened and the cycle is repeated.
The rail delivery pressure is modulated between 250
a n d 1 6 0 0 b a r s ( 3 6 2 5 t o 2 3 2 0 6 p s i . ) b y t h e
EDC7UC31 control unit, through the pressure
regulator solenoid valve.
The pump is lubricated and cooled by the fuel.
The pump replacement time on the engine is highly
reduced in comparison with traditional injection
pumps, because it does not require timing.
IMPORTANT: If the line between the fuel filter and
high pressure pump is to be removed or replaced, be
sure that components are absolutely clean.
COMMON RAIL
BS06K066 Figure 2-65
COMMON RAIL
The common rail volume is a high pressure fuel
storage device. It has a small volume to allow a rapid
pressurization at startup, at slow idle and in case of
high flow rates.
It has enough volume to minimize system spikes
caused by injector opening and closings and by the
high pressure pump operation. This function is
further enhanced by a calibrated orifice between the
high pressure pump and the common rail.
A fuel rail pressure sensor (1) is screwed into the
common rail. The signal sent by this sensor to the
EDC7UC31 control unit, and is then feed back to the
common rail pressure sensor and corrected if
necessary.
1