2.9.1 Supply system

  Important

• The high pressure supply injection system is highly susceptible to damage if the fuel is contaminated.
• It is crucial that all components of the injection circuit are thoroughly cleaned before the components are removed.
• Thoroughly wash and clean the engine before maintenance.
• Contamination in the fuel supply injection system may cause a reduction in effectiveness / operation of engine fault indication.
• If the engine is cleaned with high pressure washer, then the nozzle must be kept at a minimum distance of 200mm from the surface, and not directed at electrical components and connectors.

The fuel supply system is under low pressure from the tank 1 to the high-pressure fuel injection pump 5.

NOTE: The representation of fuel tank is purely  indicative. Component not necessarily supplied by KOHLER.

Tab 2.12

2.9.2 Fuel return circuit

The fuel return circuit is under low pressure.

NOTE: The representation of fuel tank is purely  indicative. Component not necessarily supplied by KOHLER.

Tab 2.13

2.9.3 Injection pump

Pressure into the injection pump must be positive in all operating conditions.
The injection pump is operated by means of the pump control gear and sends high-pressure fuel to the injectors. 

NOTE: In the event of leakage from the high pressure circuit do not  intervene with the engine running, but turn it off and wait 5 - 10 minutes before checking the leak.

Tab 2.14

2.9.4 Injector

It is a device used to introduce fuel, in the form of one or more jets that are adequately pulverised and suitably oriented directly into the combustion chamber. They consist of a metallic body that internally provides a mobile element that acts on the needle: this, rising against the action of a calibrated spring,
allows the release of fuel under high pressure.

Important

• The injectors are calibrated individually.
• Fuel contamination causes serious damage to the injection system.

Tab 2.15

2.9.5 Fuel filter

The fuel filter is situated on the crankcase of the engine or it may be assembled on the frame of the vehicle.

Tab 2.16

2.9.6 Electric fuel pump (optional)

When the electric fuel pump is installed in a diesel engine, one must:

1. Remove any filters installed on the inlet of the electric fuel pump;
2. Insert a pre-filter between the tank and the electric pump;
3. The electric pump must be installed on the application at a height from the minimum tank level such as to generate a MAX. pressure drop equal to a column of 500 mm of fuel;
4. Insert a shut-off valve to prevent dry operation due to the emptying of the intake manifold;
5. The electric pump must guarantee a supply pressure at the inlet positive in all conditions.

Tab 2.18

Fig 2.10

 

2.9.7 Guards for fuel injection circuit components

High-pressure injection circuit components are particularly sensitive to impurities.
To prevent impurities, even microscopic ones, from accessing the fuel input or output unions, you are required to close these accesses by means of specific caps as soon as the various tubes are disassembled and disconnected.

Disassembly of any component of the injection circuit must not occur in dusty environments.

Cap guards must remain closed in their housing (ST_40) until the moment they are to be used.

Pay special attention when using the caps and avoid any contamination of dust or dirt of any kind.

Even after using the caps illustrated in this paragraph, all components of the injection circuit must be placed with care in environments that are free of any type of impurity.

Fig. 2.11 and 2.12 illustrate the caps that must be used on components of the injection circuit.

Cap guards must be accurately washed after use and placed back in their housing (ST_40).

  Important

• It is highly recommended to have this page visible during disassembly operations of the components of the fuel injection circuit.