New Holland 667TA/EBF, Repair Manual

Page: 87 / 150

2-69
87519804 NA Issued 11-06 Bur
CHAPTER 2 - 667TA ENGINE OVERHAUL
ENGINE REPAIR MANUAL
TEST ON THE PRESSURE RELIEF VALVE ON
THE COMMON RAIL
BS06K217 Figure 2-90
The pressure relief valve is installed on the end of the
common rail, its function is to protect the systems
components if any malfunction causes and excessive
increase in the pressure of the high pressure system.
Disconnect recirculation line (1) from the pressure
relief valve and plug with the VOSS fitting from the
test set.
No diesel must come out of the valve at any engine
speed. If the diagnostic system signals a fault code
“Engine - backfill valve control”, it means that the
EDC7UC31 control unit has recognized that the
value has opened after a significant change in the
pressure of the rail greater than 1700 bar (24656
psi.). Since its opening is to be considered a
consequence of abnormal increase in pressure, the
valve is NOT defective even though a great amount
of diesel flows out.
If the valve seeps diesel without a fault code, then
replace the valve.
With the common rail pressure sensor disconnected
and a fault code is generated, with the rail pressure is
a t 7 1 0 b a r ( 1 0 2 9 8 p s i . ) m e a s u ra bl e w i t h t h e
diagnostic instrument, the trouble is in the wiring and
not the component.
IMPORTANT: Information acquired to date shows that the sensor is rarely defective.
1