LAND ROVER DEFENDER 1996 Owners Manual

19FUEL SYSTEM
4
DESCRIPTION AND OPERATION
110/130 TWIN TANK FUEL SYSTEM - 5 DOOR
VEHICLES
1.Fuel filter
2.Supply pipe, lift pump to filter
3.Supply pipe, filter to injection pump
4.Fuel injection pump
5.Fuel lift pump
6.Spill return pipe, injection pump to change-over
tap
7.Supply pipe, fuel tank change-over tap to lift
pump
8.Spill return pipe, change-over tap to side tank
9.Change-over tap, spill return
10.Fuel filler cap
11.Side fuel tank12.Supply pipe, side tank to sedimentor
13.Sedimentor, if fitted, side tank
14.Supply pipe, sedimentor to fuel tank
change-over tap
15.Change-over tap, side and rear tanks
16.Supply pipe, rear sedimentor to fuel tank
change-over tap
17.Spill return pipe, change-over tap to rear tank
18.Rear fuel tank
19.Fuel filler pipe
20.Breather pipe
21.Supply pipe, rear tank to sedimentor
22.Sedimentor, if fitted, rear tank
NOTE: If sedimentors are not fitted, the
fuel supply pipe from the side and rear
tanks connects directly to the fuel tank
change-over tap.

FUEL SYSTEM
5
DESCRIPTION AND OPERATION
110/130 TWIN TANK FUEL SYSTEM - 2 DOOR
VEHICLES
1.Fuel filter
2.Supply pipe, fuel lift pump to filter
3.Supply pipe, filter to injection pump
4.Injection pump
5.Fuel lift pump
6.Spill return pipe, injection pump to change-over
tap
7.Supply pipe, fuel tank change-over tap to lift
pump
8.Side fuel tank
9.Spill return pipe, change-over tap to side tank
10.Change-over tap, spill return
11.Supply pipe, side tank to sedimentor
12.Fuel filler pipe13.Breather pipe
14.Sedimentor, if fitted, side tank
15.Supply pipe, sedimentor to fuel tank
change-over tap
16.Change-over tap, fuel tanks
17.Supply pipe, rear sedimentor to fuel tank
change-over tap
18.Spill return pipe, change-over tap to rear tank
19.Rear fuel tank
20.Fuel filler pipe
21.Breather pipe
22.Supply pipe, rear tank to sedimentor
23.Rear sedimentor, if fitted
NOTE: If sedimentors are not fitted, the
fuel supply pipe from the side and rear
tanks connects directly to the fuel tank
change-over tap.

19FUEL SYSTEM
6
DESCRIPTION AND OPERATION
TWIN TANK FUEL CHANGE - OVER MECHANISM
1.Change-over tap, fuel tanks
2.Fuel supply, side tank
3.Fuel supply, rear tank
4.To fuel lift pump
5.Change-over tap, spill return
6.Spill return, side tank
7.Spill return, rear tank8.Spill return, injection pump to change-over tap
9.Control rod, operating lever to fuel change-over
tap
10.Control rod, change-over lever to spill return
pivot bracket
11.Fuel tank change-over switch
12.Control lever

FUEL SYSTEM
7
DESCRIPTION AND OPERATION
FUEL SYSTEM COMPONENT LOCATION
1.Fuel filter bleed screw
2.Fuel filter
3.Turbocharger
4.Actuator
5.Air cleaner
6.Fuel injector7.Heater plug
8.Heater plug controller
9.Coolant temperature transmitter
10.Fuel injection pump
11.Fuel lift pump
12.Intercooler

19FUEL SYSTEM
8
DESCRIPTION AND OPERATION
EGR FUEL SYSTEM COMPONENT LOCATION, (when fitted)
1.EGR modulator valve
2.Electrical harness plug
3.Vacuum spill pipe, modulator to air cleaner hose
4.Vacuum pipe, brake servo hose to modulator
valve
5.'T' piece connector
6.Vacuum pipe, vacuum pump to brake servo7.EGR valve
8.Vacuum pipe, modulator valve to EGR valve
9.Multi-plug connector, EGR valve
10.EGR control unit (fixed on base of centre seat or
cubby box)
11.EGR throttle position sensor

FUEL SYSTEM
9
DESCRIPTION AND OPERATION OPERATION
Diesel engines operate by compression ignition. The
rapid compression of air in the cylinder during the
compression cycle heats the air and when fuel is
injected into the heated air, it ignites instantaneously.
During cold tarting, automatically controlled heater
plugs assist in raising the temperature of the
compressed air to ignition point.
A cold start advance unit advances the injection timing
to further assist starting. Idle quality is improved by
the high idle setting.
The engine is supplied with pre-compressed air by a
single stage turbocharger.
Exhaust gases passing over a turbine cause it to
rotate, driving a compressor mounted on the turbine
shaft. Air drawn from the cold air intake passes, via
the air cleaner, to the turbocharger where it is
compressed. Compression in the turbocharger warms
up the air considerably, so that it expands. As a result
the air mass per cylinder is reduced, having a
negative effect on power output. By fitting a charge-air
intercooler, located on the LH side of the radiator, the
air is cooled before reaching the cylinders. This
increases power output through increased mass of
oxygen in the combustion process, as well as
maximising engine durability, through maintaining
lower piston and head temperatures.
Fuel is drawn from the tank by a mechanical lift pump
and passes to the injection pump via a filter. In
addition to removing particle contamination from the
fuel, the filter incorporates a water separator, which
removes and stores water.
The sedimentor/s, when fitted, is located adjacent to
the fuel tank/s and separates contamination and water
particles in the fuel before reaching the fuel lift pump.
The injection pump meters a precisely timed, exact
quantity of fuel to the injectors in response to throttle
variations, injection timing varying with engine speed.
Any excess fuel delivered to the injection pump is
passed back to the tank via the spill return line.
Fuel is injected in a finely atomised form into the main
combustion chamber, the burning fuel expands
rapidly, creating extreme turbulence which mixes the
burning fuel thoroughly with the compressed air,
providing complete combustion.Cold Starting is assisted by heater plugs, a cold start
advance unit and a high idle setting.
Heater plugs
Heater plug operation is controlled by a timer unit,
start relay and resistor. When the ignition is turned on
the timer unit is energised, the heater plugs start to
operate and a warning light on the dashboard
illuminates, remaining on until the heater plugs are
automatically switched off.
The length of time the heater plugs will operate is
dependent on under bonnet temperature, which is
monitored by a sensor located in the timer unit.
Starting the engine results in the power supply to the
heater plugs passing through the resistor, which
reduces their operating temperature. The heater plugs
are cut out either by the temperature sensor in the
timer, or by a microswitch on the injection pump which
operates when the throttle is depressed.
Cold start advance
The cold start advance unit is connected to the engine
cooling system via hoses. It contains a temperature
sensitive element which is retracted when cold and
pulls the advance lever, via cable, towards the rear of
the pump against spring pressure. As coolant
temperature rises, the cold start element expands
releasing tension on the cable and allowing spring
pressure to move the advance lever forwards.
Exhaust gas recirculation (EGR), when fitted
Operation of the EGR system is dependent on the
following:
·Engine temperature - must be between 20°C and
100°C approx.
·Engine speed - must be between 630 and 2850
rev/min.
·Engine load - calculated by throttle position
sensor.
·EGR valve lift position.
·Duration of engine idling.

19FUEL SYSTEM
10
DESCRIPTION AND OPERATION Under varying engine speed and load condition the
control unit sends a signal to open the vacuum
modulator which allows a vacuum to be applied above
the EGR diaphragm. The vacuum supply is taken from
a 'T' connector in the brake servo hose. This process
is controlled by an engine speed/load map stored in
the EGR control unit memory.
Engine speed is measured by monitoring the
waveform present on one phase of the generator.
Throttle position is measured via a sensor mounted on
the fuel injection pump throttle lever. Closed loop
control is achieved by allowing the control unit (ECU)
to continually monitor EGR valve lift via the sensor
mounted on the valve; this valve lift is compared with
the actual valve lift required on the control unit map
and adjusted, if necessary.
With coolant temperature between 20°C and 100°C,
the engine having just returned to idle, EGR will shut
off after 25-30 seconds idling.

FUEL SYSTEM
1
ADJUSTMENT THROTTLE CABLE
Adjust
1.Slacken throttle cable adjustment ferrule.
2.Hold throttle lever in fully closed position.
3.Adjust outer cable, by rotating ferrule, to give
1,57 mm (1/16 in) of deflection in the inner cable.
4.Check that throttle opens fully when the throttle
is depressed.EGR THROTTLE POSITION SENSOR
Check
1.Run engine until normal operating temperature is
reached.
2.Switch off engine and disconnect throttle position
sensor multi-plug.
3.Connect an Ohmmeter across pins 1 and 3 of
multi-plug. Ohmmeter should read between 1K
and 1.05K ohms.
4.Connect Ohmmeter across pins 1 and 2 of
multi-plug. Ohmmeter should read between 850
and 900 ohms.
5.If readings are correct, reconnect multi-plug.
6.If readings are not obtained slacken 2 torx
screws securing sensor.
7.Rotate sensor to obtain correct Ohmmeter
reading, then tighten torx screws.
8.Re-check readings and fit multiplug.
9.If, after adjustment, Ohmmeter readings cannot
be achieved, fit new sensor.
See Repair, EGR
throttle position sensor

19FUEL SYSTEM
2
ADJUSTMENT LOW AND HIGH IDLE SPEED ADJUSTMENT
NOTE: The high idle speed (cold start idle)
is automatically set by the setting of the
low idle speed and cannot be adjusted
individually.
1.Check and adjust throttle cable.
See Throttle
cable
2.Start engine and run it until normal operating
temperature is reached.
3.Using a suitable tachometer, check the engine
idle speed,
See ENGINE TUNING DATA,
Information, 300Tdi
4.If adjustment is necessary, first slacken the
locknut on injection pump.
5.Turn adjustment screw clockwise to increase
engine speed or anti-clockwise to decrease the
speed. Run engine at an increased speed for a
few seconds then check idle speed again.
6.When correct speed has been achieved, hold
adjuster screw steady while tightening locknut.
NOTE: The low idle speed control is the
only permitted adjustment in service. Any
additional adjustments required must be
entrusted to authorised Bosch agents.THROTTLE PEDAL ADJUSTMENT
Adjust
1.First ensure that throttle cable is correctly
adjusted
See Throttle cable
2.Depress throttle pedal, by hand, to full extent of
injection pump lever travel. Slacken locknut and
adjust throttle pedal stop screw to take up
clearance between screw and bulkhead. Ensure
no strain is placed upon throttle cable and pump
lever.
3.Retighten locknut.

FUEL SYSTEM
3
ADJUSTMENT INJECTION PUMP TIMING - CHECK AND ADJUST
Service repair no - 19.30.01
1.Viewing the valve mechanism through oil filler
aperture, turn crankshaft clockwise until inlet
valve of No.1 cylinder has just closed. No.1
cylinder is now just before TDC.
2.Remove blanking plug from flywheel housing
and insert timing toolLRT-12-044, locating
centre pin on flywheel.
NOTE: A chassis undertray may be fitted
on some vehicle derivatives to conform to
legal requirements. When under chassis
adjustments or remove and refit procedures are
required, it may be necessary to remove the
undertray and/or integral access panels.
See
CHASSIS AND BODY, Repair, Front undertray
or
See CHASSIS AND BODY, Repair, Rear undertray
3.Cearfully rotate crankshaft clockwise until centre
pin engages timing slot in flywheel.
4.Remove injection pump access plate, complete
with gasket, from front cover plate.
5.Fit locking pinLRT-12-045/2to injection pump
gear. If difficulty is experienced in inserting pin,
adjustments will be needed to correctly set
injection pump timing as follows:
6.Support injection pump retaining nut to prevent
strain on timing belt.
7.Slacken the 3 keeper plate retaining bolts.
8.Carefully turn fixing nut and keeper plate until
locking pin can be inserted, without restriction,
into injection pump gear.
9.Tighten keeper plate bolts to
25 Nm (18 lbf/ft)
and remove locking pin.
10.Refit injection pump access plate plate and
gasket.
11.Remove flywheel timing tool and refit blanking
plug.
12.Run engine until normal operating temperature is
reached and check that idle speed adjustment,
See low and high idle speed adjustmentand
throttle cable adjustment
See Throttle cable
are correct.