1999 LAND ROVER DEFENDER Workshop Manual

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.
ProCarManuals.com

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.
ProCarManuals.com

ProCarManuals.com

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.
ProCarManuals.com

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.
ProCarManuals.com

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.
ProCarManuals.com

19FUEL SYSTEM
2
REPAIR SWITCH - INERTIA - FUEL CUT OFF
Service repair no - 19.22.09
Remove
1.Disconnect multiplug from fuel cut off switch.
2.Remove 2 screws securing switch to bulkhead.
3.Remove switch.
Refit
4.Position switch to bulkhead.
5.Fit screws securing switch to bulkhead.
6.Connect multiplug.
7.Press top of switch to set switch.SENSOR - MASS AIR FLOW (MAF)
Service repair no - 19.22.25
Remove
1.Disconnect multiplug from MAF sensor.
2.Loosen clip screw and release air intake hose
from MAF sensor.
3.Release 2 clips and remove sensor from air
cleaner.
Refit
4.Position sensor to air cleaner and secure clips.
5.Position air intake hose and tighten clip screw.
6.Connect multiplug.
ProCarManuals.com

FUEL SYSTEM
3
REPAIR SENSOR - COMBINED MAP AND IAT
Service repair no - 19.22.26
Remove
1.Remove 3 bolts and remove engine acoustic
cover.
2.Disconnect multiplug from combined MAP and
IAT sensor,
3.Remove 2 bolts securing sensor to inlet
manifold.
4.Remove sensor and discard’O’ring.
Refit
5.Clean sensor and mating face.
6.Fit new’O’ring and position sensor to manifold.
7.Fit and tighten MAF and IAT sensor bolts to9
Nm (7 lbf.ft)
8.Fit engine acoustic cover and secure with bolts.SENSOR - AMBIENT AIR PRESSURE (AAP)
Service repair no - 19.22.27
Remove
1.Disconnect multiplug from AAP sensor.
2.Remove 2 screws and remove sensor.
3.Remove and discard’O’ring.
Refit
4.Clean sensor and air cleaner cover.
5.Fit new’O’ring, fit sensor and tighten screws.
6.Connect multiplug to AAP sensor.
ProCarManuals.com