Yanmar 4TNV98, Service Manual

Page: 178 / 246

4TNV98 & 4TNE98 Diesel Engine Section 4. Fuel System 176
Process
Suction Process
Figure 7-10
Figure 7-11
When the inlet port of the plunger barrel overlaps
the inlet slit of the plunger during the lowering
process of the plunger, the fuel in the pump
chamber is drawn into the plunger.
Injection Process
Figure 7-12
Figure 7-13
The plunger begins rotating at the same time the
lifting process of the cam disc begins. When the
inlet port of the plunger barrel is covered by the
plunger, pressure feeding of fuel is initiated. At the
same time, the highly pressurized fuel presses up
the delivery valve when the outlet slit of the plunger
meets the outlet port of the plunger barrel. The fuel
is then injected into the engine combustion
chamber via the nozzle and nozzle holder.