Ford Falcon. Manual — part 181

303-04c-12

Single Fuel LPG

303-04c-12

DESCRIPTION AND OPERATION (Continued)

UTE - Through each of the wheel arches (2

Automatic Fill Limiter

valves to shut off supply) .

The system incorporates an Automatic Fill Limiter

WAGON - From underneath the vehicle between

(AFL), which prevents the tank being filled with liquid

the rear axle and the front cylinder.

beyond 80% of the tank volume. The 20% vapour

The excess flow valve will automatically close to a

space is necessary to allow for expansion of the liquid

trickle and shut off the supply of liquid if an

that occurs as temperature increases. The AFL

abnormally high flow rate occurs. This may occur if

incorporates a non-return valve.

the fuel supply line is ruptured or damaged. The

Variant

Tank Capacity

80% of Total

service valve incorporates a pipe that extends to the

(100%)

Capacity (AFL)

bottom of the tank to ensure that only liquid LPG is

Sedan

115 litres

93 litres of LPG

withdrawn and directed to the converter.

Wagon

145 litres

116 litres of

Pressure Relief Valves/Hydrostatic Valve

LPG

A pressure relief valve is located on each tank and on

Ute

114 litres

92 litres of LPG

the service line Hydrostatic Valve located:

Service Valve and Solenoid Operated Shut

UTE only - near the bottom of the firewall.

Off Valve

Should the pressure at the relief valve(s) on the

tank(s) reach approximately 2.55MPa, the valve will

The Service Valve consists of a solenoid operated,

open and discharge excess pressure to the

normally closed shut off valve, a manual-isolating

atmosphere. The Hydrostatic Valve on the liquid

valve and, an excess flow valve.

service line performs the same function but at

The solenoid operated shut off valve is energised only 3.10MPa. Once the pressure reduces below that

when the vehicle is starting or the vehicle’s engine is

pressure the valve will close automatically. During

running. When the valve is de-energised, it prevents

normal operating and under normal ambient

the flow of LPG from the tank.

conditions there is no reason for the relief valve to

operate.

Wagon & Ute

NOTE: The pressure relief valves are NOT a

serviceable item.

Fuel Contents Gauge

Each LPG tank fuel gauge/sender unit has a float

similar to a petrol gauge unit. (i.e. it will float up and

down with the liquid level in the tank.)
The fuel gauge will indicate FULL when the LPG liquid

level is at 80% of each tank capacity. The LPG tank

sender is interfaced with the vehicle dash mounted

fuel gauge and indicates total amount of fuel.

Fill Valve

The fill valve consists of a valve with a soft seat and a

soft housing. The fill valve is connected to the AFL

Item

Description

mounted on the tank by a flexible pressure hose.

1

Service valve

Fuel Line and Filter Lock Off

2

Service line

3

Solenoid operated shut off valve

The fuel line is made of Bundy tubing and transports

liquid LPG from both tanks to the Filter/Lock Off

4

Fuel contents gauge with sender unit

Valve. This valve is integral with the converter and

5

AFL (Automatic Fill Limiter)

incorporates a filter and a magnet to prevent foreign

The manual isolating valves enable the liquid supply

particles interfering with the operation of the Lock Off

to the converter to be shut off in the event of an

Valve.

accident or during servicing. These can be accessed

The Filter/Lock Off is a safety device designed to

from various regions depending on the variant.

prevent the flow of liquid to the converter when the

SEDAN - From underneath the vehicle in the

engine is not running or cranking. They are controlled

stone plate service cut out (between the two

electronically by the PCM when the engine is running.

cylinders).

If the engine stalls or the ignition is left switched ON,

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Single Fuel LPG

303-04c-13

DESCRIPTION AND OPERATION (Continued)

the PCM will switch OFF the supply of LPG

coolant to prevent the converter from freezing as the

automatically.

vaporising gas draws heat from the atmosphere. The

converter is located in the engine bay and is attached

Converter

by a bracket to the right hand spring tower.

The converter is a two-stage pressure regulator,

which incorporates a heat exchanger, prime circuit

and idle circuit. The heat exchanger uses engine

below 35 kPa the primary valve opens. If the pressure

Item

Description

is above 35 kPa the valve closes. This action

1

Stepper Motor

maintains primary pressure at the correct level. As the

2

Prime Solenoid

liquid enters the primary chamber and the pressure

drops it boils and a change of state to gas occurs. A

3

Prime Hose

large amount of heat energy (latent heat of

4

Mount Bracket

vaporisation) is absorbed during this change of state

5

Coolant Outlet

and it is therefore necessary to pass hot engine

6

Coolant Inlet

coolant through a jacket in the converter body to

prevent the converter from freezing up.

7

Inlet Gas Lock Off Solenoid

NOTE: If the converter freezes at any time during its

8

Liquid Gas Inlet

life, it may be damaged internally. This will affect the

9

Filter & Magnet

vehicles driveability and continued safe operation. A

10

Drain Plugs

registered LPG technician should inspect/repair the

11

Idle Solenoid

converter.

12

Balance Hose Fitting

Regular maintenance of the cooling system, coolant

13

Vapour Line Fitting

level and anti-freeze is very important to ensure

correct operation of converter. From the primary

First Stage

chamber the vapour moves through two different

paths: The idle circuit and the secondary valve.

Liquid enters the converter at tank pressure

(approximately between 750-1280 kPa). It is then

reduced to a pressure of approximately 36 kPa (5.5

psi) in the primary chamber. If the pressure drops

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Single Fuel LPG

303-04c-14

DESCRIPTION AND OPERATION (Continued)

central bore via the sensitive diaphragm. This

Second Stage

stabilises the pressure in the central bore and stops

Second stage LPG flow is controlled by a secondary

the secondary valve from opening more. As the

valve. The force needed to overcome the secondary

secondary valve is partially open, vapour also leaves

spring pressure and therefore control the flow, is

the primary chamber through the secondary valve.

acquired from the flow amplifier system within the idle

As the engine speed increases, the pressure through

circuit and from the engine vacuum signal present in

the gas/air mixer reduces which in turn reduces the

the secondary stage. The idle circuit, which

pressure in the secondary chamber. As the secondary

incorporates the flow amplifier, remains open for as

chamber pressure reduces, the sensitive diaphragm

long as the engine is running. Flow through this

restricts the flow of vapour to the central bore. This

section is stopped by the idle solenoid when the

causes the central bore pressure to drop further, and

engine stops turning. Note that, at idle the LPG

therefore, open the secondary valve more.

vapour is supplied through both the idle circuit and the

As the secondary valve releases more vapour, the

secondary valve.

pressure in the secondary chamber is increased and

Prime Valve

the sensitive diaphragm allows more vapour into the

central bore. Once the pressures are balanced the

A prime solenoid is incorporated to permit primary

secondary valve reaches an equilibrium point and

pressure LPG to go directly to the engine via the

steady state flow is maintained.

stepper motor housing during starting. The stepper

motor does not directly control this initial primary

Air Cleaner

pressure gas flow. The prime circuit is fed LPG from

The air cleaner is unique on this LPG vehicle. It

the idle circuit.

includes a pipe to fit the balance hose to and also has

Heat Shield

unique springs, which allow the pressure of backfire to

escape.

The exhaust manifold heat shield has an extension

that protects the bottom of the converter and liquid

Ram Air Balance Hose

service line.

The System includes a Ram air balance hose

connected between the converter and the air cleaner

base. The purpose of the Ram air balance is to

provide the converter with the correct pressure levels

inside the intake system, as the pressure levels will

vary away from atmospheric due to the positive Ram

air effect built up in front of the vehicle at highway

speeds. The varying pressure levels have an

influence on the positioning of the sensitive

diaphragm within the converter and ultimately the

Ram air balance assists in ensuring that the converter

is supplying gas to the engine in quantities suitable to

the current and varying operating requirements.

Stepper Motor

The stepper motor is bolted directly to the converter at

Operation Summary

the vapour outlet and is connected to the mixer by a

vapour hose. The stepper motor is a bipolar unit with

Liquid LPG flows from the tank through the converter

two independently controlled coils. The rotational

lock off and up to the primary valve. As the liquid LPG

motion of the motor is converted to a linear pintle

passes through the primary valve, the pressure is

movement via a screw drive. In normal operation the

reduced to 35 kPa and the liquid vaporises as it

pintle extends and retracts as commanded by the

passes through the primary chamber. From the

PCM. This trims the flow of LPG vapour to the engine

primary chamber the vapour either passes through

allowing closed loop EGO (Exhaust Gas Oxygen)

the idle circuit or the secondary valve. The prime

content control.

valve is fitted to the converter for starting. LPG at

primary pressure flows from the idle circuit to the

Fuel Gauge and Instrument Cluster

prime valve lock off only while the idle solenoid is

energised.

The LPG fuel level signal from the sender is sent

directly to the instrument cluster. The fuel gauge will

The idle vapour passes through the idle jet to the flow

show the total amount of fuel in the cylinders. The

amplifier and then into the secondary chamber. As the

PCM transmits the fuel usage to the cluster, to be

vapour passes through the flow amplifier, it draws

used in the ’Range’ calculation, over the CAN line.

vapour out of the central bore. The pressure in the

central bore is reduced and the secondary valve is

opened. At the same time vapour is leaking into the

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Single Fuel LPG

303-04c-15

DESCRIPTION AND OPERATION (Continued)

Pin

Label

Function

C26

GSCC

Stepper motor coil

connection C

C27

GSCD

Stepper motor coil

connection D

C7

GCO

Solenoid relay trigger

(grounding signal)

C21

PRIME

LPG Prime Solenoid

Solenoid Operation

Three solenoids valves on the sedan and wagon and

four solenoid valves on the Ute, as mentioned above,

are energized continuously whenever LPG operation

is required. The engine must be running before the

LPG Solenoid Valves

valves will open. The valves are de-energised when

ignition is turned off or the engine stops. The prime

The LPG system has number of solenoid valves

solenoid is operated independently of the other

depending on the variant:

solenoids by the EEC in most starting conditions.

SEDAN has four solenoid valves - one tank lock

off, an engine-bay lock off, an idle circuit solenoid

Stepper Motor Operation

and a prime solenoid.

The main LPG control is performed by the stepper

WAGON has four solenoid valves - one tank lock

motor. The pintle moves back and forth over a range

off, an engine-bay lock off, an idle circuit solenoid

of 255 steps to trim the LPG flow. A step position of

and a prime solenoid.

255 is fully closed and 0 is fully open. Normal

UTE has five solenoid valves - two tank lock offs,

operation is in the range of 100 to 200 steps. The

an engine-bay lock off, an idle circuit solenoid and New Generation Star Tester (NGS) or WDS can

a prime solenoid.

monitor and log the stepper motor step position.

All of the solenoids are controlled by the PCM. All

Reset Procedure

solenoids, except the prime, are switched together by

a relay and fuse mounted near the PCM.

The stepper motor is reset by the EEC during starting

to initialise the pintle position. The pintle ramps

Wiring Loom

towards the fully open position and continues pushing

The wiring connects circuits at the LPG tank,

into the seat for a number of steps to guarantee that

converter, PCM and fuse panel. The PCM therefore

the motor is in a known open position. The motor then

performs all of the control functions. The

extends to a normal operating position. When coolant

solenoid-switching relay and fuse are directly mounted temperature (ECT) is below 20°C and engine off time

to the harness near the PCM. For protection, the relay is between 1 to 10 minutes, the stepper motor will

is covered by a moulded sheathe. The wiring

open fully to determine its zero position and then

diagrams and connector pinouts are detailed in the

close immediately. the stepper motor will then slowly

wiring schematic section (section 9).

open to its normal operating position. This is to protect

against the possibility of rich starting under these

PCM

conditions.

The PCM has direct control of the LPG stepper motor

Open Loop Operation

and switches four LPG solenoids via a relay. The

PCM also controls the prime solenoid. The PCM has

The open loop stepper motor position is determined

also been specially calibrated to control the ignition

within the PCM based on several operating

and transmission systems when running on LPG. This parameters. This is calculated from engine and inlet

ensures that the vehicle is operating at peak

air temperatures and A/C status. The engine operates

performance and efficiency.

in open loop in similar situations to petrol:

Post start - 20 to 45 seconds depending on

LPG related PCM pins

temperature.

Pin

Label

Function

Wide-open throttle

C24

GSCA

Stepper motor coil

The adaptive learn system also adds a learnt step

connection A

position offset.

C25

GSCB

Stepper motor coil

connection B

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