Ford Falcon. Manual — part 183
303-04c-20
Single Fuel LPG
303-04c-20
DIAGNOSIS AND TESTING
solution, specifically formulated for this purpose, eg.
Single Fuel LPG
not cause corrosion of steel lines, etc. Electronic
combustible gas detectors are also regularly used by
Inspection and Verification
many Technicians. Refer to the operating instructions
supplied with either method to ensure accuracy and
WARNING: Where testing procedures require safety when leak testing.
the handling of LPG of which may result in the
release of LPG the following precautions must be
Leak testing procedure
taken:
The fuel system must contain sufficient LPG liquid to
Disconnect and safely stow the vehicles
ensure a minimum vapour pressure of 450 kPa,
battery earth lead. (The lead may require
otherwise a leak check will not be valid.
reconnection for certain tests involving
NOTE: The pressure in the cylinder (tank) is related to
electrically operated components.)
the temperature of the LPG rather than the liquid
The working area and working procedures
level.
must comply with Australian Standards (AS)
2746.
Where possible run the engine to ensure all
components are supplied with liquid LPG.
When the tank is being filled, the normal
precautions applicable to petrol or LPG
Begin by testing:
service station areas must be observed. i.e.
all the tank and filler fittings
No smoking and no ignition sources within the
service line joints
working zone - ignition off and parking brake
all filter/lock-off and converter connections and
engaged.
joints.
If for any reason the tank is filled beyond the
A large leak can actually blow away the foam solution
80% level, the vehicle can be driven without
and not produce any bubbles. This must be carefully
stopping the engine for a sufficient distance
monitored.
(approx. 150 km) to consume the excess fuel.
If this is not possible the excess fuel must be
Remember since LPG is heavier than air, test
removed by de-canting (refer Removal and
thoroughly below all fittings and components.
Installation) or by one of the methods for fuel
Where a leak is indicated, remake the joint, using a
unloading as described in Australian
suitable sealing compound. The seal compound used
Standards (AS) 2746.
must be specifically suitable for LPG applications.
NOTE: All workshops performing repairs/
maintenance on LPG equipped vehicles should be
CAUTION: Leaking joints with parallel
registered and in possession of, and technicians
threads and seats are uncommon. If this type of
familiar with, the contents of standards AS/NZS 1425- joint leaks, check for correct torque. If the leak
1999 and AS 2746.
persists after re-torquing, the joint must be
replaced. Thread sealing compounds should not
Leak Detection Methods
be used to seal these types of joints.
There are several acceptable methods such as:
NOTE: When using a liquid leak detection method,
the liquid must be mopped from the cylinder at the
Combustible gas detectors
completion of the test to prevent corrosion.
Trace gas detectors
Foam
LPG Tank Assembly
Total immersion
Each tank assembly comprises:
Visual inspection
The tank shell and valve PAD.
Refer to standards AS/NZS 1425-1999 for a complete
Automatic fill limiter.
description including advantages or disadvantages of
Tank gauge.
each of the above mentioned leak detection methods.
Safety valve.
High pressure leak testing
Service valve with integral excess flow valve.
A high pressure leak check of the LPG system must
Test
be carried out at each service. The standard AS/NZS
1425-1999 requires that this be carried out at least
Pressure test with an inert gas (eg. Nitrogen) in
annually. In most cases this would fall in line with one accordance with the following procedure.
of the 15,000 kilometre intervals.
WARNING: Oxygen must NOT be used for
Leak testing equipment
pressurising, furthermore compressed air can be
The most common method of leak detection is to use
dangerous in association with LPG and a tank
a foam test solution. It should be a proprietary leak
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303-04c-21
Single Fuel LPG
303-04c-21
DIAGNOSIS AND TESTING (Continued)
which has previously contained LPG must be
Automatic Fill Limiter
thoroughly purged with Nitrogen if it is intended
The accuracy of the shut-off function of the automatic
to use compressed air for pressurising.
fill limiter should be checked with the vehicle standing
Close the service valve.
on level ground and the tyres correctly inflated in
Pressurise the container to an internal pressure of accordance with standard AS/NZS 1425-1999.
2.3
± 0.05 MPa.
The container must be emptied of liquid LPG and then
Remove the pressurising attachment.
filled by a pump meter unit. The pump meter reading
at which the AFL cuts off shall be within
± 2% of the
Check all joints between the container and the
maximum permitted filling volume i.e. 80% of the
components for leaks (refer Leak Detection
capacity of the container.
Methods).
The capacity must be less than 92 litres for Ute, 93
Check the filler valve and the service valve for
litres for Sedan and 116 litres for Wagon .
leakage through the valve seats.
NOTE: The accuracy of the contents gauge may be
With the valve outlet plugged or capped and the
checked at the same time.
valve opened, check for leaks at the valve stem
seal of any valve that is normally open in service.
Excess Flow Valve
Where a leak is indicated, rectify the fault by
replacement or resealing, and retest the area.
To test the function of the excess flow valve in
accordance with AS/NZS 1425-1999 follow the steps
Testing the Installation
as listed below:
The following procedure should be applied after the
Using compressed air or a gas inert to LPG,
tank sub assembly has passed the required test and
pressurise the LPG cylinder to an internal
has been installed in the vehicle.
pressure 2.3 MPa as per clause 4.2.2 of AS/NZS
1425-1999.
WARNING: It is essential that all air be
Fully disconnect the service line from the AXIOM
purged from the container before LPG pressure
solenoid service valve.
tests commence, and it is more convenient if this
Fully close the manual hand tap on the AXIOM
purging is carried out before the container is
solenoid service valve.
installed.
Remove the solenoid coil, solenoid piston sleeve
and solenoid piston.
Leak testing of gas system
Quickly open the manual hand tap on the valve
After all connections have been made, the LPG
and check that the excess flow valve functions.
system should be tested for leaks as follows:
WARNING: If the service line is to be
WARNING: It is important that high propane
disconnected, first remove the battery and take
LPG, (not high butane LPG) be used for this test
steps to ensure that discharging gas does not
because it has a relatively high vapour pressure at
become a hazard.
the lowest temperatures likely to occur in a
workshop. The pressure gauge on the LPG supply Manual valve
tank can be taken to represent the container
Open and close the manual valve and test around
pressure reasonably accurately, and if below 450
glands and connections for leaks.
kPa, testing should be postponed. Under no
circumstances should the container be heated to
Lock Off Solenoids (At Cylinders and
raise the pressure.
Converter)
Place high propane LPG in the container and
Start the engine.
ensure that the liquid lines are full of liquid phase
Disconnect the solenoid connector plug at the
LPG.
converter or both solenoid connector plugs on the
Test all pipe and component connections,
cylinders (one on each) depending on which
including those on remote filling lines, and test the
solenoid(s) you are testing.
filler valve.
When the LPG in the converter and supply lines
Where a leak is indicated, rectify the fault by
has been used up the engine should stop.
remaking or replacing the joint, and retest the
If the engine continues to run it indicates that
area.
either the lock off piston is not sealing or the
solenoid(s) are inoperative.
To test the solenoid electrically a resistance
measurement needs to be taken. The correct
resistance is: 12.6 Ohms
± 4% at 20°C.
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303-04c-22
Single Fuel LPG
303-04c-22
DIAGNOSIS AND TESTING (Continued)
1. No air should come out of the prime solenoid.
Fuel Filler
2. Idle solenoid still energised.
Check for damage to the coupling and for the
6. Energise the prime solenoid.
presence of foreign matter, and check that the cap is
attached correctly. Check that the sealing washer is in
1. High pressure air should come out of it.
place and in good order. Check that the housing
7. De-Energise prime solenoid high pressure air
containing the filler valve is soundly attached to the
should stop coming out (returns to idle flow).
vehicle, and that the remote fill line is not deformed or
8. De-Energise prime and idle solenoids first then
damaged by twisting resulting from a loose housing or
de-energise lock off solenoid.
mounting.
9. Disconnect air supply. Do not shake the
Water system tests
converter.
The water circulation system which supplies radiator
1. Converter should hold pressure for at least 10
water to the converter should be pressure tested for
minutes.
leaks, using a conventional radiator pressure testing
2. Test pressure retention by gently inserting a
method.
blunt object into the central hole of the rear
cover. Air will be heard to escape from the
Converter
vapour outlet.
Converter freeze-up
3. Soap test complete converter for leaks
Converter freezing will occur if insufficient heat is
including water inlet and outlet, atmospheric
available to support the change of state from liquid
vent fitting and backcover openings when
LPG to a gas. This can occur if the radiator coolant
converter does not hold pressure.
level is low or there is a restriction of some kind in the 10. If converter passes above test, remove hose.
converter coolant hoses, or air inlet to radiator.
11. Converter is now ready for installation.
A heat exchanger is included in the converter which is
Worldwide Diagnostic System (WDS) Tester
supplied with engine coolant. In the event of freeze up
occuring, back flush the hoses and heat exchanger
The WDS tester can display the stepper motor
and check coolant flow to converter.
position and LPG fuel level as well as all the usual
functions.
Should the engine stall or lose power, particularly
under hard acceleration, promptly inspect converter
Stepper Motor
for signs of freezing. Freezing can cause internal
leaking and damage within the converter.
Stepper Motor Position
Bench Testing Converter
The stepper motor moves in discrete steps from 0
(fully open) to 255 (fully closed). The step rate will
1. Place converter with diaphragms in vertical
vary from 250 steps per second to 2 steps per
position making sure that the atmospheric vent
second. During a reset procedure, the motor is
fitting in the front cover is free of obstructions and commanded to step 0 to drive the pintle wide open. It
that the converter lock off is energised.
should then retract to approximately step 150. In
1. Do not energize idle solenoid.
normal operation, the motor should sit in the range of
120-200 steps. During steady state open loop
2. There should be no air coming out the vapour
operation, the step position will stay near constant. In
outlet or water chamber openings.
closed loop, the position will oscillate 10 to 20 steps to
2. Apply air pressure of 6-20 BAR (80-280 psi) to
maintain a constant air-fuel ratio.
fuel inlet.
3. Energize idle solenoid and inlet gas lock off
Condition
Step Position
HEGO output
solenoid.
Stepper motor
0-150
N/A
1. Air should be coming out at vapour outlet.
reset
(APPROX.)
2. Converter may slightly pulse air at vapour
Closed loop
~100-200
oscillates
outlet. This is normal.
between rich
and lean
4. Install a hose to front cover atmospheric vent
fitting.
High throttle
~60-130
rich
openings
1. Blow on hose with mouth.
Other open loop ~100-160
rich or lean
2. Air flow should increase each time you blow
on hose.
LPG Self Test — KOER
5. Disconnect prime hose.
The LPG self test checks that the HEGO output
responds to movements in the stepper motor. This is
performed during the KOER test. The engine must be
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303-04c-23
Single Fuel LPG
303-04c-23
DIAGNOSIS AND TESTING (Continued)
warm before the test is started. The PCM increases
Disconnect LPG solenoids in the engine bay.
the engine speed to approximately 1300 rpm. The
Start engine.
stepper motor is ramped towards 180 steps or until
Engine will start and stop running shortly
the HEGO reads a lean signal. The motor is then
afterwards as the residual fuel is used up.
ramped towards 50 steps or until the HEGO reads a
Remove Stepper Motor Housing:
rich signal. Engine speed may drop slightly and run a
little rough during this phase. The engine speed
Undo the two M6 cap screws that secure the
should then drop once. Failure to maintain engine
stepper motor body to the converter.
speed or switch to rich and then lean within a
Leave the stepper motor connected to the
specified time will result in a test fault (P1159 - Fuel
housing.
Stepper Motor Fault). The stepper motor fault can be
Stepper Motor Pintle Movement:
due to many factors and not just the stepper motor
Inspect stepper motor pintle and housing for
itself.
foreign matter or water.
Stepper Motor Movement Check - Manual
Observe pintle through the LPG vapour outlet.
This test will establish whether the stepper motor is
Start the engine.
being correctly driven through its reset procedure. A
The pintle should smoothly extend to fully open
failure in this test could be due to a problem in the
the outlet and then go to approximately half of its
PCM, wiring or the motor itself.
full travel.
LPG Runout
The engine should stop running immediately
Stop engine
afterwards due to lack of fuel.
Symptom Charts
WARNING: Before removal of any valves or fuel gauge, the LPG tank must be emptied. Refer to
“Decanting of Tank”, in the Removal and Installation chapter.
Service Valve
Condition
Source
Action
Foreign matter between valve seat
Will not shut off.
Remove
foreign
material.
hand tap.
Damaged shaft.
Replace hand tap assembly.
Leaking valve stem. Excess flow valve
Damaged or worn seal.
Replace seal.
not operating/responding too early.
Defective valve.
Replace valve.
Damaged flare connection.
Mishandling.
Replace nipple.
Excess flow valve locked closed on
Turn off manual hand tap and wait for
Defective automatic fill flow valve.
cylinder containing LPG preventing
valve to unseat. Then replace valve.
decanting tank.
Automatic Fill Limiter (AFL) .
Condition
Source
Action
Confirm with second fill at different
Fills slowly/will not fill.
Damaged automatic fill limiter (AFL).
bowser on a different day to ensure
the issue isn’t related to fuel,
temperature or bowser pressure.
Replace automatic fill limiter (AFL)
Over/under filling.
Incorrect positioning of float.
Confirm with second fill.
Float defective.
If faulty, replace AFL.
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