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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