Yanmar 4LHA-HTP User Manual

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Chapter 3 Fuel Injection Equipment
4. Fuel System
, 4LHA Serie:
4. Fuel System
Fuel filter
Overflow pipe
••D
Drive shaft
Overflow valve
Sedimenter
Regulating valve
Plunger barrel
Feed pump
Plunger
1
Nozzle
Fuel tank
Fig. 2 Fuel system
Figure 2 shows an example of a fuel system.
The injection pump drive shaft is turned by the
engine's timing belt (or gear) and fuel oil is
drawn by the injection pump's feed pump
through the sedimenter and fuel filter to the in-
jection pump's fuel oil inlet.
The fuel filter acts to filter the fuel oil, and the
sedimenter is located in the lower portion of
the fuel filter to remove moisture from the fuel
system.
With drive shaft rotation the fuel oil sucked
into the feed pump is pressurized by the feed
pump and fills the injection pump chamber. The
fuel oil pressure is proportional to drive shaft
speed, and when it exceeds a specified pres-
sure excess fuel again returns to the inlet side
through a regulating valve located at the feed
pump's fuel oil outlet.
The fuel oil in the injection pump chamber
flows through the distributor head inlet into the
pressure chamber, where plunger rotation and
reciprocating motion increase its pressure. The
fuel oil is then delivered through the injection
pipe to the nozzle and nozzle holder.
An overflow valve located at the top of the in-
jection pump functions to maintain a constant
fuel oil temperature in the pump chamber by
returning excess fuel oil to the fuel tank.
S-1-5

Yanmar 4LHA-HTP Specifications

General

Brand	Yanmar
Model	4LHA-HTP
Category	Engine
Language	English