LAND ROVER DEFENDER 1999 Workshop Manual

19FUEL SYSTEM
6
DESCRIPTION AND OPERATION The fuel pressure regulator is located in a machined port in the lower part of the housing. The regulator is sealed
in the housing with two’O’rings and secured with an internal clip.
The regulator maintains the fuel pump delivery pressure at 4 bar (58 lbf.in
2). When the fuel pressure exceeds 4
bar (58 lbf.in2), the regulator opens and allows fuel to return to the fuel tank via the fuel cooler. The fuel returned
from the regulator is directed back into the fuel filter before being drawn by the high pressure stage of the fuel
pump and directed back to the injectors. A special tool can be attached to the regulator housing fuel feed port and
allows for the fitment of a suitable gauge to measure fuel pump delivery pressure.
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FUEL SYSTEM
7
DESCRIPTION AND OPERATION INJECTORS
1.Solenoid housing
2.Electrical connector
3.Push rod socket
4.Push rod return spring
5.Housing
6.Fuel delivery port7.Fuel return port
8.Nozzle cap nut
9.Copper washer
10.Nozzle
11.’O’ring
12.Cap screw
The five injectors are located in the cylinder head adjacent the camshaft, with the nozzle of each injector
protruding directly into the cylinder. Each injector is sealed into the cylinder head with a’O’ring and copper
washer and secured with a clamp and bolt.
Each injector is operated mechanically by an overhead camshaft and rocker, and electrically by a solenoid
controlled by the ECM. Each injector is supplied with pressurised fuel from the pump via the regulator housing and
internal drillings in the cylinder head.
The solenoid housing is secured to the injector body with two cap screws and is a sealed unit. It has a two pin
electrical connector on its top face.
The injector body is machined from a forging. The body has a machined central bore which locates the push rod.
A thread on the outer diameter provides the attachment for the nozzle cap nut. The body also provides attachment
for the solenoid housing.
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19FUEL SYSTEM
8
DESCRIPTION AND OPERATION The injector push rod is operated from the rocker and cam assembly by a sprocket. The push rod is located in the
housing bore and retained in its extended position by a push rod return spring. The powerful spring ensures that
the push rod socket is always in contact with the rocking lever and the cam.
The lower part of the injector housing locates the spring loaded nozzle. The nozzle is retained in the housing by a
nozzle cap nut which is screwed onto the housing. The nozzle cap nut has four holes around its circumference
which connect to the fuel pump drilling in the cylinder head. The injector housing has ports located above the
nozzle cap nut which connect with the fuel delivery drilling in the cylinder head. An’O’ring seals the injector in the
machined location in the cylinder head and a copper washer seals the injector from the combustion chamber.
The injectors are supplied with pressurised fuel from the fuel pump via the pressure regulator housing and internal
drillings in the cylinder head. Each injector sprays fuel directly into the cylinder at approximately 1500 bar (22000
lbf.in) atomising the fuel and mixing it with intake air prior to combustion.
The camshaft and rocker arrangement depresses the push rod which pressurises the fuel within the injector.
When the injector is required to inject fuel into the cylinder, the ECM energises the solenoid which closes a valve
within the solenoid housing. The closure of the valve stops the fuel entering the return line to the pump, trapping it
in the injector. The compression of the fuel by the push rod causes rapid pressurisation of the fuel which lifts the
injector nozzle, forcing the fuel into the cylinder at high pressure. The ECM controls the injection timing by altering
the time at which the solenoid is energised and the injection period by controlling the period for which the solenoid
is energised.
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FUEL SYSTEM
9
DESCRIPTION AND OPERATION FUEL FILTER
1.Filter body
2.Nut
3.Bolt
4.Rubber washer
5.Water sensor6.Filter element
7.Air bleed valve
8.Air bleed connection
9.Copper washer
10.Connector
The fuel filter is mounted on the chassis longitudinal below the rear RH wheel arch. The filter has four quick
release coupling connections; low pressure feed from the fuel pump, low pressure return to the fuel pump, return
line from the fuel pressure regulator and a bleed line to the fuel pump. The fuel filter removes particulate matter
from the fuel and also separates water which accumulates at the bottom of the filter.
An air bleed valve is located in the bleed line connection. The valve comprises a restrictor and a membrane. The
restrictor has a small hole in its centre. This allows air and fuel to pass through the membrane. Air can pass
through the membrane, but once the membrane is wet with fuel, it will not allow further fuel to pass through.
The fuel filter has a replaceable screw-on cannister type filter element which is sealed to the filter body with rubber
seals. The lower part of the cannister has a screw connection for a water sensor. The filter has a flow rate of 180
litres/hour (47.6 US Gallons/hour).
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19FUEL SYSTEM
10
DESCRIPTION AND OPERATION WATER SENSOR
The water sensor has a three pin electrical connector. When the sensor detects water in the fuel filter it illuminates
a warning lamp in the instrument pack.
The water sensor attachment thread has a slot machined down one side. The filter can be purged of water by
partially unscrewing the sensor which aligns the slot in the threads with a corresponding hole in the sensor. When
aligned, water and fuel can flow down the slot and flows from a small cast tube on the side of the sensor.
Re-tightening the sensor mis-aligns the slot and stops the flow of fuel.
The sensor operates by measuring the resistance between its two electrodes, which are submerged in fuel, and
activated by the presence of water. When the ignition switch is moved to position’II’, the warning lamp will
illuminate for approximately 2 seconds to check warning lamp functionality.
When the filter is full with fuel and no water is present, the resistance of the Diesel fuel will show a reading of 15
mA maximum on the feed wire to the instrument pack. When sufficient water surrounds both electrodes, the
resistance of the water will show a reading of 130 mA maximum. This will supply sufficient voltage to the
instrument pack to illuminate the warning lamp, and alert the driver to the presence of water in the fuel system.
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FUEL SYSTEM
11
DESCRIPTION AND OPERATION OPERATION
The low pressure stage of the fuel pump draws fuel from the swirl pot and pumps it into the fuel filter. The high
pressure stage of the fuel pump draws the fuel from the fuel filter and pumps it along the fuel feed pipe to the
cylinder head.
The fuel enters the cylinder head through a connection on the fuel pressure regulator housing and supplies each
injector with pressurised fuel. The fuel pressure regulator maintains the fuel pressure at the injectors at 4 bar (58
lbf.in) by returning excess fuel back to the fuel filter. The returned fuel passes through the fuel cooler in the engine
compartment before it passes to the fuel filter.
When the engine is running, each injector is operated by an overhead camshaft which depresses a push rod in
each injector at a timed interval. When the cam has depressed the push rod and the push rod is returning to its
extended position, fuel is drawn from the fuel supply drilling in the injector.
When the ECM determines that injection is required, the ECM transmits an electrical pulse which energises the
fast acting solenoid, closing the spill valve on the injector and locking fuel in the injector body. As the cam begins
to depress the push rod, the fuel in the injector is rapidly pressurised. When the pressure exceeds the nozzle
spring pressure, the nozzle opens and injects fuel at very high pressure into the cylinder.
When the ECM determines that the injection period should end, the solenoid is rapidly de-energised, opening the
spill valve on the injector and allowing fuel to pass into the return circuit.
The ECM controls the injection timing by altering the time at which the solenoid is energised, and the injection
period by controlling the period for which the solenoid is energised.
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FUEL SYSTEM
1
ADJUSTMENT HEATER PLUG TEST
Service repair no - 19.90.20.01
Check
1. Test out of engine
2.Remove heater plug.See Repair.
3.UsingLRT-12-511,connect RED lead to battery
’+’positive and the BLACK lead to battery’-’
negative.
4.Position heater plug into tester and retain with
spring loaded bar.
5.Connect YELLOW lead to heater plug terminal.
6.Press red button on tester and note ammeter
reading. Keep button depressed, heater plug tip
should start to glow after 5 seconds
CAUTION: The heater plug tip must glow
first, if it fails to do so, replace heater plug.
7.The ammeter reading should show an initial
current draw of 25 amps, which should fall to 12
amps after 20 seconds.
8.Refit heater plug.See Repair.FUEL SYSTEM - BLEED
Service repair no - 19.50.07
Fuel Purging Procedure
1.If the vehicle runs out of fuel, or the fuel level is
so low that the fuel system draws air into the fuel
rail, the fuel rail will need to be purged before the
engine will start. This can be achieved by
following a set procedure. The process does not
require the use of any specialist equipment and
can be performed by the driver of the vehicle.
The process is as follows:
2.Switch off ignition and wait 15 seconds.
3.Turn ignition key to position 2 and wait 3
minutes, (this ensures that the fuel system
purges all the air from the fuel rail within the
cylinder head).
4.Depress the throttle pedal to more than 90% of
its total travel, (to the throttle stop).
5.Crank the engine keeping the throttle pedal
depressed.
NOTE: This operation is controlled by the
ECM and it is important that the purging
operation is not carried out on a vehicle
that has not run out of fuel. If it is carried out
unnecessarily it can lead to the engine flooding
and failing to start.
This operation will be cancelled:
6.As soon as engine speed exceeds 600 rev/min.
7.The driver allows the throttle pedal to close to a
position less than 90% of its travel.
8.The ignition key is released from the start
position.
NOTE: The engine must not be cranked for
more than 30 seconds in any one period.
9.Repeat the above procedure if the engine fails to
start.
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19FUEL SYSTEM
2
ADJUSTMENT FUEL TANK - DRAIN
Service repair no - 19.55.02
1.Remove battery cover.
2.Disconnect both leads from battery, earth lead
first.
WARNING: Fuel vapour is highly
flammable and in contained spaces is also
explosive and toxic. Always have a fire
extinguisher containing FOAM, CO2, GAS OR
POWDER close at hand when handling or draining
fuel.
3.Using a fuel recovery appliance, drain the fuel
from the tank into a sealed container. Follow the
manufacturers instructions for the connection
and safe use of the appliance.
4.Remove filler cap and insert hose into filler neck.
5.Connect bowser earth line. Drain fuel.
6.Connect battery leads.
7.Fit battery cover.
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FUEL SYSTEM
1
REPAIR ELEMENT - AIR FILTER
Service repair no - 19.10.10
Remove
1.Release 2 clips and disconnect air flow meter
from air filter cover.
2.Disconnect multiplug from AAP sensor.
3.Release 2 clips and remove cover from air filter.
4.Remove air filter element.
Refit
5.Clean air filter body and cover.
6.Fit new air filter element.
7.Position air cleaner cover and secure clips.
8.Position air flow meter and secure clips.
9.Connect AAP sensor multiplug.SENSOR - FUEL TEMPERATURE
Service repair no - 19.22.08
Remove
1.Remove 3 bolts and remove engine acoustic
cover.
2.Release fixings and remove battery cover.
3.Disconnect battery negative lead.
4.Disconnect multiplug from fuel temperature
sensor.
5.Thoroughly clean area around fuel temperature
sensor before removal.
6.Remove fuel temperature sensor and discard
sealing washer.
Refit
7.Clean fuel temperature sensor mating faces.
8.Fit new sealing washer and tighten fuel
temperature sensor to13 Nm (9 lbf. ft).
9.Connect multiplug to fuel temperature sensor.
10.Reconnect battery negative lead.
11.Fit battery cover and secure fixings.
12.Fit engine acoustic cover and secure with bolts.
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