1996 LAND ROVER DEFENDER Workshop Manual

19FUEL SYSTEM
2
DESCRIPTION AND OPERATION A mechanical lift pump, with a hand priming facility, is
driven by the camshaft, and is mounted on the RH
side of the engine.
A fuel filter, with a replaceable element and
incorporating a water separator, is mounted on the
front RH side of the engine compartment.
A fuel sedimentor may be fitted when the vehicle is
operating in more arduous conditions, and is used to
minimise water deposits in the fuel system before
reaching the fuel pump and filter.
Fuel injection is carried out by a Bosch direct injection
pump, incorporating a cold start advance unit and a
high idle setting. The pump is mounted on the RH side
of the engine and is driven directly by gears in the
front cover from the crankshaft. The pump meters and
distributes fuel to 4 pintle type injectors located in
pre-combustion chambers in the cylinder head. Four
heater plugs, located in the cylinder head directly
below each injector, are fitted to improve cold starting.
An optional hand throttle, for use with a centre power
take off, is located on the fascia to the LH side of the
fuse box, and is linked independently to the fuel
injection pump throttle lever.
Air intake
The air cleaner is mounted on the RH side of the
engine and is connected by hoses to the cold air
intake duct and turbocharger inlet. Fitted between the
air cleaner and turbocharger is the crankcase breather
hose which connects to a breather filter on the rocker
cover.
A single stage turbocharger, fitted between the
exhaust manifold and exhaust down pipe, is
connected by hoses to the air cleaner and an
intercooler which is mounted on the LH side of the
radiator. The intercooler is connected by a hose to the
inlet manifold. When an EGR valve is fitted to the
turbocharger, additional pipes/hoses are used to
connect the components.Exhaust gas recirculation (EGR), when fitted.
Exhaust gas recirculation is controlled by an ECU
mounted under the front centre seat or cubby box and
receives the following inputs:
·Engine temperature from coolant temperature
sender unit on LH side of cylinder head.
·Throttle position from potentiometer on injection
pump.
·Engine speed from speedometer.
When all correct signals are received, the EGR
solenoid allows vacuum to open EGR valve and
recirculate a portion of the exhaust gas. See J6196 for
the EGR system component location and 'Operation'
for full system function.

FUEL SYSTEM
3
DESCRIPTION AND OPERATION
90 FUEL SYSTEM
110 FUEL SYSTEM
1.Fuel filter
2.Supply pipe, lift pump to filter
3.Supply pipe, fuel filter to injection pump
4.Fuel injection pump
5.Fuel lift pump
6.Spill return pipe, injection pump to tank7.Supply pipe, sedimentor to fuel pump
8.Fuel tank
9.Supply pipe, fuel tank to sedimentor
10.Fuel filler pipe
11.Breather pipe
12.Sedimentor, if fitted
NOTE: If a sedimentor is not fitted, the fuel
supply pipe from the tank will connect
directly to the fuel lift pump.

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.