DAF CF65, CF75, CF85 Series . Manual — part 443

©

200324

2-9

General

PE ENGINE FUEL SYSTEM

CF65/75/85 series

4

5

Fuel filter
The fuel filter consists of a filter housing (1) with a

screw cap (2) in which the filter element (3) is

secured. The inner section of the filter housing

contains a central tube (4) with a supply side (A)

and a permanent bleed side (B).

The fuel enters via connection (5) and is forced

through the filter element (3). Within the filter

element is the central tube (4) with the supply

side (A) and a permanent bleed side (B). Via

bores in the supply side (A), the filtered fuel

passes to the pump housing.

A small section of the fuel and any air present

enters via a calibrated hole (6) on the top of the

central tube (4) in the permanent bleed side (B)

and is led to the bottom of the filter housing.

At the bottom of the filter housing, a small amount

of fuel and any air present are mixed with the

leak-off fuel from the injectors (9) and the excess

fuel from the pump housing (10). In the

connection of the injector leak-off pipe is a banjo

bolt with an integrated non-return valve (11).

From the bottom of the filter housing, the excess

fuel and any air present go back to the tank (7).

A B

A

B

i400424

6

2

5

10

8

7

7

8

9

1

3

11

4

PE ENGINE FUEL SYSTEM

2-10

©

200324

General

5

CF65/75/85 series

4

Pump unit
The valve (6), back plate (8) and the pump

plunger (13) are located in the top of the pump

unit.

These parts are lubricated by the fuel.

A roller (17), tappet (15) and a spring (14) with

spring retainer (16) are situated on the bottom of

the pump unit.

These parts are lubricated by the engine

lubrication system.

The lower sealing ring on the pump unit

separates the fuel system from the engine

lubrication system.

A pressure valve (5) is fitted on the top of the

pump unit.

The function of the pressure valve is to prevent

the supply section from being interrupted by

pressure peaks from the injector pipe.

The injection timing and the quantity of fuel to be

injected are controlled by a solenoid valve (9) that

consists of an electromagnet and valve (6) with

back plate (8), via the electronic unit control.

If the solenoid valve (9) is not energised, the

valve (6) is forced against the valve stop (4) by

the force of the valve spring.

This creates a very small opening between the

space above the pump plunger (13) and the

supply ducts (2).

The fuel will now flow via the fuel supply ducts (2)

to the space above the pump plunger (13).

1

15

17

3

4

6

7

8

10

2

11

12

13

14

16

9

i 400434

5

©

200324

2-11

General

PE ENGINE FUEL SYSTEM

CF65/75/85 series

4

5

If the solenoid valve (9) is energised by the

electronic unit, the back plate (8) with the valve

(6) will be attracted by the electromagnet due to

the influence of the magnetic field.

The valve (6) closes the connection between the

space above the pump plunger (13) and the

supply ducts (2), causing pressure to build up in

the space above the plunger (13).

This causes an injection.

The valve (6) is not re-opened against the force

of the magnet by the high-pressure in the high-

pressure area, as the forces in the valve (6) slot

are balanced.

In other words, the left and right surfaces in the

valve (6) slot are equal.

The time at which the valve (6) shuts depends on

the injection timing calculated by the electronic

unit.

The time that the valve (6) remains closed, and

therefore the quantity of fuel injected, is also

calculated by the electronic unit.

1

15

17

3

4

6

7

8

10

2

11

12

13

14

16

9

i 400435

5

PE ENGINE FUEL SYSTEM

2-12

©

200324

General

5

CF65/75/85 series

4

Pressure relief valve
To guarantee a good degree of filling of the pump

units, the end of the supply channel has a

pressure-relief valve.

The pressure-relief valve connects the supply

channel to the discharge channel.

The fuel flows into the entrance (1), past the

piston (2) and the guide pin (3) and to the exit (4).

The fuel encounters resistance due to the

presence of the spring (5). This results in a

pressure-relief valve opening pressure of approx.

5 bar.

The piston (2) has a diagonal bore (6). This bore

is fitted for bleeding the fuel system.

2.4 CRANKING THE ENGINE

Cranking on the flywheel housing
1.

Place the special tool (DAF no. 1310477) on

the opening at the bottom of the flywheel

housing such that the pinion engages the

starter ring gear.

2.

Turn the crankshaft clockwise as seen from

the timing gear end (this corresponds to the

direction of rotation of the engine).

4

6

1

2

3

5

i400423

M201187