Husqvarna Prelude 350 Instruction manual

Workshop manual
English
340 345 346XP
350 351 353
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English – 1
Workshop manual
Husqvarna 340/345/346XP/350/351/353
Contents
Introduction ........................................................... 2
Safety regulations ................................................. 3
General instructions ........................................... 3
Special instructions ............................................ 3
Special tools .......................................................... 4
Technical data ....................................................... 6
Construction and function ................................... 8
Carburettor ......................................................... 8
Troubleshooting .................................................. 10
Repair instructions ............................................. 12
Chain brake ...................................................... 12
Silencer ............................................................ 14
Chain catcher ................................................... 14
Stop switch ....................................................... 15
Stop switch – resistance measurement ........... 15
Choke control ................................................... 16
Throttle trigger .................................................. 17
Hand grip heater .............................................. 18
Starter assembly .............................................. 21
Starter cord ...................................................... 21
Recoil spring .................................................... 22
Ignition module – testing .................................. 23
Ignition module and flywheel ............................ 23
Generator ......................................................... 24
Centrifugal clutch ............................................. 26
Oil pump ........................................................... 27
Carburettor ....................................................... 30
Carburettor – pressure testing ......................... 33
Carburettor heater ............................................ 34
Air intake system .............................................. 35
Carburettor – adjustment ................................. 37
Fuel tank .......................................................... 38
Fuel filter .......................................................... 39
Fuel hose ......................................................... 39
Piston and cylinder ........................................... 41
Decompression valve – pressure testing ......... 42
Cylinder – pressure testing .............................. 44
Crankcase and crankshaft ............................... 45
Crankshaft bearings ......................................... 46
Repairing damaged threads ............................. 49
Thread insert .................................................... 49
Guide bar bolts ................................................. 49
Appendix A, Carburettor – EPA models ........... 50
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2– English
Arrangement of the manual
This workshop manual can be used in two different
ways.
• To repair a specific sub-assembly on a chainsaw.
• To dismantle and reassemble a complete
chainsaw.
Repairing a specific sub-assembly
If a specific sub-assembly on the chainsaw needs
to be repaired:
1. Look up the page referring to the relevant sub-
assembly.
2. Follow the instructions under the headings:
Removal/Dismantling
Cleaning and inspection
Refitting/Reassembly
Dismantling and reassembling the entire
chainsaw
If the entire chainsaw is to be dismantled, follow
the instructions under the heading “Removal/
Dismantling”.
Work through the manual and follow the instruc-
tions given in each section under the heading
“Removal/Dismantling”.
Then follow all the “Cleaning and inspection”
instructions in each section.
Working from the back of the manual, follow all the
instructions under the headings “Refitting/
Reassembly” in reverse order.
Each of the sections covering removal/dismantling
and refitting/reassembly include the relevant
lubrication instructions and bolt torques for each
stage of repair.
Construction and function
This chapter gives a simple description of the
chainsaw carburettor and its various parts.
Introduction
Troubleshooting
These pages describe the most common faults that
affect a chainsaw. They are divided into four
different groups with the most likely faults de-
scribed first.
Repair instructions
The section that describes how to repair the
chainsaw consists of detailed, step-by-step instruc-
tions. It explains in detail the special tools, lubri-
cants and bolt torques that are needed when
working on each component.
This workshop manual covers the following
chainsaw models:
340
345
346XP
350
351
353
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English – 3
General instructions
This workshop manual gives detailed instructions
on how to troubleshoot, repair and test a chainsaw.
This section also describes the various safety
precautions that should be taken when carrying out
repairs.
The workshop manual has been written for person-
nel who are assumed to have general experience
of repairing and servicing chainsaws.
Workshops where chainsaws are repaired must be
equipped with safety equipment that meets local
regulations.
No-one should carry out repairs on a chainsaw
until they have read and understood the contents
of this workshop manual.
Chainsaws are type-approved to meet the relevant
safety legislation, but this only applies when the
saw is fitted with the cutting equipment specified in
the user’s manual. The fitting of any other equip-
ment, or of accessories or parts that are not
approved by Jonsered, could mean that the saw no
longer meets these safety requirements and the
person who carried out the work may be held
responsible for its non-conformance.
In this workshop manual the following boxes
indicate where caution should be taken.
Special instructions
The fuel that is used in a chainsaw poses the
following hazards:
• The fuel and its fumes are toxic.
• May cause irritation to skin or eyes.
• May cause breathing difficulties.
• Highly flammable.
When using compressed air the air jet should
never be pointed at the body. Air can be forced into
the bloodstream and cause fatal injury.
Wear ear protection when testing saws.
After testing a saw do not touch the silencer until it
has cooled down. The silencer gets very hot and
you may burn yourself. Wear protective gloves
when working on the silencer.
The guide bar, chain and clutch cover (chain brake)
must be fitted before the saw is started. If not, the
clutch may come loose and cause injury.
Poor chain lubrication can result in failure of the
chain, which could cause serious or fatal injury.
Take care to ensure that the spring inside the
starter assembly does not fly out and cause injury.
Wear eye protection. If the spring is under com-
pression when the pulley is removed it could fly out
and cause injury.
Before removing the tensioning spring from the
chain brake, ensure that the brake is in the on
position, otherwise the spring may fly out and
cause injury.
After completing the repair the chain brake must be
tested, see “Chain brake – reassembly \ Operating
test”.
Always consider the fire risk. A chainsaw can
produce sparks that could start a fire.
Inspect the chain catcher and replace it if it is
damaged.
WARNING!
The warning text warns of the risk
of personal injury if the instruc-
tions are not followed.
NOTE!
The warning text warns of the risk of
material damage if the instructions are
not followed.
Safety regulations
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4– English
Special tools
45
8
11 12 10
123
14
6
97
13
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English – 5
Item Description Used for Order no.
1 Clutch tool Centrifugal clutch 502 54 16-01
2 Piston stop Locking crankshaft 502 54 15-01
3 Stop plate Locating intake gaiter 502 54 17-01
4 Fuel filter hook Withdrawing the fuel filter 502 50 83-01
5 Allen key For M5 bolts 502 50 18-01
6 Puller Frame bearing 504 90 90-02
7 Removal tool Remove seal from clutch side 502 50 55-01
8 Mandrel, sealing ring Removing crankshaft 502 54 21-01
9 Cover plate Sealing during pressure testing 502 54 11-02
10 Pressure tester Connection to cylinder 503 84 40-02
11 Feeler gauge Adjusting ignition module 502 51 34-02
12 Clamp stand Clamping the saw 502 51 02-01
13 Pressure gauge Pressurisation during testing 502 50 38-01
14 Piston fitting kit Fitting piston 502 50 70-01
15 Test plug Checking ignition module 502 71 13-01
16 Rev counter Adjusting carburettor 502 71 14-01
17 Removal tool Removing crankshaft 502 51 61-01
18 Vacuum gauge Vacuum test 502 50 37-01
19 Assembly pliers Fitting spark plug guard 502 50 06-01
20a Sleeve Fitting crankshaft 502 50 30-18
20b Shaft extension Flywheel side 502 50 30-18
20c Shaft extension Clutch side 502 50 30-18
21 Stop plate Removing crankshaft 502 54 18-01
22 Assembly tool Assembling spring, chain brake 502 50 67-01
23 Crankshaft tool Fitting crankshaft seal 502 50 30-16
Special tools
15 16
20 b
21
19
17
20 c
20 a
18
22
23
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6– English
Displacement Cylinder bore Stroke Max power/speed
cm3/cubic inches Ø mm/Ø inches mm/inches kW/hp/rpm
340: 40,8 / 2,44 40 / 1,57" 32 / 1,28" 2,0 / 2,7 / 9 000
345: 45,0 / 2,75 42 / 1,65" 32 / 1,28" 2,2 / 3,0 / 9 000
346XP/G: 45,0 / 2,75 42 / 1,65" 32 / 1,28" 2,5 / 3,4 / 9 600
350: 49,4 / 3,01 44 / 1,73" 32 / 1,28" 2,3 / 3,1 / 9 000
350 EPA: 51,7 / 3,15 45 / 1,77" 32 / 1,28" 2,3 / 3,1 / 9 000
351/G: 49,4 / 3,01 44 / 1,73" 32 / 1,28" 2,3 / 3,1 / 9 000
353/G: 51,7 / 3,15 45 / 1,77" 32 / 1,28" 2,4 / 3,3 / 9 000
Spark plug gap Ignition system Air gap Carburettor type
mm/inches mm/inches
340: 0,5 / 0,02" SEM CD 0,3 / 0,012" Walbro HDA 195
345: 0,5 / 0,02" SEM CD 0,3 / 0,012" Walbro HDA 195
346XP/G: 0,5 / 0,02" SEM CD 0,3 / 0,012" Zama C3-EL17
350: 0,5 / 0,02" SEM CD 0,3 / 0,012" Walbro HDA 195
350 EPA: 0,5 / 0,02" SEM CD 0,3 / 0,012" Zama C3-EL18
351/G: 0,5 / 0,02" SEM CD 0,3 / 0,012" Zama C3-EL17
353/G: 0,5 / 0,02" SEM CD 0,3 / 0,012" Zama C3-EL17
Effective cutting length Chain speed at Chain pitch Drive link
cm/inches max power – revs mm/inches mm/inches
m/s – rpm
340: 30-48 / 12"-19" 17,3 / 9 000 8,25 / 0,325" 1,3 / 0,050" - 1,5 / 0,058"
345: 30-48 / 12"-19" 17,3 / 9 000 8,25 / 0,325" 1,3 / 0,050" - 1,5 / 0,058"
346XP/G: 30-48 / 12"-19" 18,5 / 9 600 8,25 / 0,325" 1,3 / 0,050" - 1,5 / 0,058"
350: 30-48 / 12"-19" 17,3 / 9 000 8,25 / 0,325" 1,3 / 0,050" - 1,5 / 0,058"
350 EPA: 30-48 / 12"-19" 17,3 / 9 000 8,25 / 0,325" 1,3 / 0,050" - 1,5 / 0,058"
351/G: 30-48 / 12"-19" 17,3 / 9 000 8,25 / 0,325" 1,3 / 0,050" - 1,5 / 0,058"
353/G: 30-48 / 12"-19" 17,3 / 9 000 8,25 / 0,325" 1,3 / 0,050" - 1,5 / 0,058"
Technical data
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English – 7
Technical data
Idling speed Engagement speed Max. speed Spark plug
rpm rpm rpm
340: 2 700 3 800 12 500 NGK BPMR 7A, Champion RCJ 7Y
345: 2 700 3 800 12 500 NGK BPMR 7A, Champion RCJ 7Y
346XP/G: 2 700 3 800 14 200 NGK BPMR 7A, Champion RCJ 7Y
350: 2 700 3 800 13 000 NGK BPMR 7A, Champion RCJ 7Y
350 EPA: 2 700 3 800 13 000 NGK BPMR 7A, Champion RCJ 7Y
351/G: 2 700 3 800 13 000 NGK BPMR 7A, Champion RCJ 7Y
353/G: 2 700 3 800 13 000 NGK BPMR 7A, Champion RCJ 7Y
Fuel tank capacity Oil pump capacity at Oil tank capacity Automatic oil pump
Litres/US pints 8,500 rpm, Litres/US pints
ml/min
340: 0,5 / 1,05 9 0,25 / 0,53 Yes
345: 0,5 / 1,05 9 0,25 / 0,53 Yes
346XP/G: 0,5 / 1,05 5 - 12 0,28 / 0,59 Yes
350: 0,5 / 1,05 5 - 12 0,26 / 0,55 Yes
350 EPA: 0,5 / 1,05 5 - 12 0,26 / 0,55 Yes
351/G: 0,5 / 1,05 5 - 12 0,28 / 0,59 Yes
353/G: 0,5 / 1,06 5 - 12 0,28 / 0,59 Yes
Weight without bar and chain Weight with bar and chain Heated hand grips
kg / lbs kg / lbs
340: 4,7 / 10,3 5,5 / 12,1 -
345: 4,7 / 10,3 5,5 / 12,1 -
346XP: 4,8 / 10,6 5,6 / 12,2 -
346XPG: 4,9 / 10,8 5,7 / 12,4 Yes
350: 4,8 / 10,6 5,6 / 12,2 -
350 EPA: 4,8 / 10,6 5,6 / 12,2 -
351: 4,8 / 10,6 5,6 / 12,2 -
351G: 4,9 / 10,8 5,7 / 12,4 Yes
353: 5,0 / 11,0 5,8 / 12,6 -
353G: 5,1 / 11,2 5,9 / 13,0 Yes
rpm
GAS
OIL
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8– English
The carburettor works in different ways depending
on the setting:
• Cold start mode
• Idling mode
• Part throttle mode
• Full throttle mode
In the cold start mode the choke valve (D) is
completely closed. This increases the vacuum in
the carburettor so that fuel is sucked through the
diffuser jets faster (E).
In idling mode the throttle valve (F) is closed. Air is
sucked through an aperture in the throttle valve
and a small amount of fuel is supplied through the
diffuser jet (E).
Construction and function
Carburettor
The carburettor consists of three sub-systems:
• The metering unit (A) which contains the jets
and the fuel control mechanism. This measures
out the right amount of fuel to suit the speed of
the saw and the power demand.
• The mixing unit (B) consists of the choke,
diffuser jets and throttle valve. This is where the
air and fuel are mixed to create a flammable
mixture.
• The pump unit (C) pumps fuel from the tank to
the metering system inside the carburettor. One
side of the pump diaphragm is connected to the
crankcase and pulses as a result of pressure
changes in the crankcase. The other side of the
diaphragm sucks in the fuel.
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English – 9
Construction and function
In part throttle mode the throttle valve (F) is par-
tially open. Fuel is supplied through the diffuser jets
(E).
In full throttle mode both valves are open and fuel
is supplied through all the diffuser jets (E).
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10 – English
Troubleshooting
Worn needle valve
Leaking control diaphragm/
cover plate
Needle valve assembly sticking
Worn needle valve lever
Faulty diffuser jet
Fuel filter blocked
Fuel line blocked
Leaking air intake hose (rubber)
Loose carburettor mounting
bolts
Worn throttle valve pivot
Loose throttle valve screw
Worn throttle valve
Needle valve assembly
sticking
Leak in metering system (air
or fuel)
Metering system centre knob
is worn
Hole in diaphragm
Leaking control diaphragm/
cover plate
Crankcase leaking
Fuel line blocked
Needle valve set too high
Needle valve assembly sticking
Leak in metering system (air
or fuel)
Leaking control diaphragm/
cover plate
Faulty diffuser jets
Crankcase leaking
Needle valve set too high
Needle valve assembly sticking
Metering system damaged
Worn needle valve
Leaking control diaphragm/
cover plate
Metering system incorrectly
assembled
Adjust L screw
Air filter blocked
Choke not working
Worn choke pivot
Worn choke valve
Fuel filter blocked
Fuel line blocked
Piston ring seized
Blocked impulse channel
Loose or faulty fuel pipe
Hole in diaphragm
Worn needle valve
Needle valve assembly sticking
Needle valve set too high
Leak in metering system (air
or fuel)
Loose cover on carburettor
pump side
Worn needle valve
Needle valve set too high
Needle valve assembly sticking
Difficulty starting
Carburettor
leaking fuel
Flooding when
engine not
running
Starting
The various faults that can affect a chainsaw are divided into four groups. In each group the likely symp-
toms are given on the left and possible causes are listed on the right. The most likely faults are given first,
and so on.
Idling (low rpm)
Idles when L
screw closed
Idling uneven
L screw requires
constant
adjustment
Too much fuel at
idling
Idling (low rpm) (cont.)
Adjust L screw
Leaking air intake hose
(rubber)
Loose carburettor mounting
bolts
Loose or faulty fuel hose
Fuel filter blocked
Fuel line blocked
Fuel tank vent blocked
Throttle valve pivot stiff
Throttle pushrod sticking
Defective throttle return spring
Bent throttle stop
Faulty diffuser jet
Adjust L screw
Worn needle valve
Needle valve set too high
Worn needle valve lever
Leaking control diaphragm/
cover plate
Needle valve assembly
sticking
Will not idle
Idling too rich
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English – 11
Troubleshooting
Acceleration and retardation
Does not
accelerate
Engine stalls
when throttle
released
Over rich
acceleration
Adjust L screw
Adjust H screw
Blocked air filter
Blocked fuel tank vent
Blocked fuel filter
Fuel line blocked
Loose or damaged fuel hose
Impulse channel blocked
Loose cover on carburettor pump
side
Faulty pump diaphragm
Leaking air intake hose (rubber)
Loose carburettor mounting bolts
Needle valve set too low
Metering system incorrectly
assembled
Needle valve assembly sticking
Faulty diffuser jets
Blocked silencer
Adjust L screw
Adjust H screw
Faulty pump diaphragm
Needle valve set too high
Needle valve assembly sticking
Faulty diffuser jets
Adjust L screw
Adjust H screw
Blocked air filter
Faulty pump diaphragm
Faulty diffuser jets
Troubleshooting methods
In addition to the faults described in the above
table, trouble shooting can be carried out on
specific components or sub-systems of the
chainsaw. The various procedures are described in
the relevant chapters, see the contents page, as
follows:
• Checking the operation of the chain brake
• Measuring the resistance of the stop plate
• Pressure testing the carburettor
• Pressure testing the decompression valve
• Pressure testing the cylinder
Adjust H screw
Blocked air filter
Blocked fuel tank vent
Blocked fuel filter
Fuel line blocked
Loose or damaged fuel hose
Impulse channel leaking
Impulse channel blocked
Loose cover on carburettor pump
side
Faulty pump diaphragm
Leaking air intake hose (rubber)
Loose carburettor mounting bolts
Needle valve set too low
Metering system damaged
Metering system incorrectly
assembled
Leaking control diaphragm/cover
plate
Needle valve assembly sticking
Blocked silencer
Adjust H screw
Blocked fuel tank vent
Blocked fuel filter
Impulse channel leaking
Impulse channel blocked
Loose cover on carburettor pump
side
Faulty pump diaphragm
Blocked air filter
Needle valve assembly sticking
Leak in metering system (air or fuel)
Metering system incorrectly
assembled
Loose diaphragm rivet
Hole in diaphragm
Leaking control diaphragm/cover
plate
Blocked fuel tank vent
Blocked fuel filter
Fuel line blocked
Loose or damaged fuel hose
Impulse channel leaking
Impulse channel blocked
Loose cover on carburettor pump
side
Faulty pump diaphragm
Leaking air intake hose (rubber)
Loose carburettor mounting bolts
Needle valve set too low
Leak in metering system (air or fuel)
Metering unit incorrectly assembled
Loose diaphragm rivet
Hole in diaphragm
Leaking control diaphragm/cover
plate
Will not run at
full throttle
Low power
Will not “four-
stroke”
High rpm
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12 – English
3
WARNING!
Make sure the spring does not fly
out and cause injury. Wear eye
protection.
Repair instructions
Chain brake – dismantling
1
Disengage the brake by pushing the kickback
guard backwards. Unscrew the guide bar bolts and
remove the clutch cover, chain and guide bar.
2
Grip the clutch cover carefully in a vice. Release
the brake spring by using the kickback guard from
the saw as a tool. Engage it with the brake mecha-
nism and turn anticlockwise to activate the brake.
Remove the screws and carefully remove the cover
from the chain brake spring.
4
Place one hand over the spring and insert a small
screwdriver between the bottom end of the spring
and the clutch cover. Carefully prise the spring
upwards so that it slides onto the screwdriver shaft.
Cleaning and inspection
• Clean and inspect all parts carefully. If there are
any cracks or other defects replace the damaged
parts with new ones. Always use original parts.
•Measure the thickness of the chain brake band.
It must be no less than 0.6 mm at any point.
•Lubricate the elbow joint with grease.
min 0,6 mm
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English – 13
Repair instructions
NOTE!
After completing the repair the chain
brake must be tested as described below.
Operating test:
The engine must not be running during the test.
Guide bar length Height
38cm/15" 50 cm/20"
• Hold the chainsaw over a firm surface. The
height of the guide bar above the surface is
given in the table above.
• Let go of the front handle and let the chainsaw
fall towards the surface.
• When the guide bar hits the surface the chain
brake must engage.
Chain brake –reassembly
1
Bolt the elbow joint to the brake band and tighten
to a torque of 1–1.5 Nm.
Locate the elbow joint and connected brake band
in their recesses in the clutch cover. Lubricate the
recess for the spring with grease.
2
Grip the clutch cover in a vice. Compress the
spring with special tool 502 50 67-01 and push it
down with your thumb.
3
Fit the cover over the chain brake spring, tightening
the screws to a torque of 1–1.5 Nm.
4
Tension the brake spring by using the kickback
guard from the saw as a tool. Engage it with the
brake mechanism and turn clockwise to release
the brake.
5
Turn the chain tensioner anticlockwise as far as it
will go.
Refit:
• guide bar
• chain
• clutch cover
WARNING!
Make sure the spring does not fly
out and cause injury. Wear eye
protection.
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14 – English
WARNING!
Do not touch the silencer until it
has cooled down, otherwise you
may burn yourself.
Repair instructions
Remove the chain catcher and replace it with a
new one. Check that the vibration damping spring
locates correctly against the crankcase when you
bolt the new chain catcher in position.
A worn (damaged) chain catcher on 340, 345 or
350 can be replaced with the same chain catcher
as 346XP, 351 and 353 (see figure above).
3
Turn the chain tensioner anticlockwise as far as it
will go.
Refit:
• guide bar
• chain
• clutch cover
Silencer –removal
Remove the cylinder cover, silencer support,
silencer, gasket and cooling plate.
2
If the saw is fitted with a spark arrestor mesh this
must also be removed.
Cleaning and inspection
Clean and inspect all parts carefully. If there are
any cracks or other defects replace the damaged
parts with new ones.
The spark arrestor mesh is best cleaned with a
wire brush. If the mesh is damaged it must be
replaced.
If the mesh is blocked the saw will overheat and
this will cause damage to cylinder and piston.
Never use the saw with a silencer that is in poor
condition. Always use original parts.
Silencer –refitting
1
If the saw is equipped with a spark arrestor mesh
this should be fitted first.
2
Refit
• cooling plate
• gasket
• silencer, tighten bolts to a torque of 8–10 Nm.
• silencer support
• cylinder cover
3
Run the saw for at least 1 minute, then retighten
the silencer bolts to 8–10 Nm.
Chain catcher –replacement
If the chain catcher is worn it must be replaced with
a new one.
1
Release the brake by pushing the kickback guard
backwards. Undo the guide bar bolts and remove
the clutch cover, chain and guide bar.
2
1
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English – 15
Repair instructions
Stop switch –removal
1
Remove the cylinder cover and air filter.
2
Disconnect both leads from the stop plate and stop
switch. Remove the stop plate by carefully sliding it
over the lug on the front mounting.
3
Carefully prise the carburettor assembly off the left-
hand rubber mounting using a small screwdriver.
4
Carefully prise the stop switch’s upper mounting off
the air filter holder while lifting the switch to release
it from the lower mounting.
Measure the resistance by connecting a multimeter
to the ignition coil. NOTE! The switch must be in
the “on” position to give the correct reading.
The resistance must not be higher than 0.2 ohm
when the switch is in the on position.
Stop switch –resistance measurement
Clean the mating surfaces and check the resist-
ance as follows:
Cleaning and inspection
Clean and inspect all parts carefully. If there are
any cracks or other defects replace the damaged
parts with new ones. Always use original parts.
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16 – English
Repair instructions
Choke control –removal
1
Remove the cylinder cover, air filter and stop
switch. Disconnect the fuel hose from the carburet-
tor.
Stop switch –refitting
1
Carefully press the new stop switch into place.
Check that the switch’s upper mounting clips over
the air filter holder.
2
Refit the stop plate. Engage the stop plate in the
front slot first then lift the rear edge onto the stop
switch. Slide the stop plate in as far as it will go.
3
Refit:
• the leads to the stop plate and stop switch
• air filter
• cylinder
Disconnect the pushrod from the carburettor by first
carefully prising up the spring over the end of the
rod, where it connects to the throttle lever (A). Then
press the throttle lever forwards (B) while pressing
the throttle pushrod backwards (C) and lifting it off
the lever. Withdraw the throttle pushrod from the
tank and lift it upwards without pulling it through the
rubber inlet manifold. Carefully release the carbu-
rettor assembly from the right-hand rubber mount-
ing and lift it upwards.
NOTE!
Do not use knurled pliers to disconnect or
reconnect the fuel hose. This could
damage the hose and lead to leakage or
fracture.
Compress the clip that holds the choke control to
the carburettor while pulling it out at the same time.
Disconnect the choke control from the air filter
holder.
3
2
C
A
B
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English – 17
Repair instructions
Cleaning and inspection
• Clean and inspect all parts carefully. If there are
any cracks or other defects replace the damaged
parts with new ones. Always use original parts.
•Lubricate the throttle lock with oil.
•Check that the spring is not broken and has not
lost its tension.
Throttle lock, throttle trigger and return
spring –refitting
1
Throttle lock, throttle trigger and return
spring –removal
1
Remove the throttle lock by pressing it to the left
(A) and carefully levering it up with a screwdriver
on the clutch side (B) of the saw to disengage the
lugs on either side of the throttle lock from the fuel
tank. When both lugs are clear of the tank, pull the
lock backwards (C).
Drive out the steel pin using a 2.5 mm/0.1" diam-
eter drift (A). Push it out from the flywheel side of
the saw. Remove the throttle trigger by first press-
ing it towards the clutch side of the saw (B) until it
clicks, then towards the flywheel side until it clicks
again. Remove it from the tank and lift out the
return spring.
2
Choke control –refitting
First reattach the choke control to the air filter, then
press it onto the carburettor so that the clips engage.
Then refit:
• stop switch
• carburettor into its rubber mountings
• throttle pushrod into the fuel tank and connect to
throttle lever.
• lift the spring arm over the throttle pushrod
• fuel hose to the carburettor
• air filter and cylinder cover
Refit the return spring to the throttle trigger as
shown. Make sure the spring is correctly positioned
by engaging one end in the slot in the throttle
trigger (A).
2
First insert the rear edge of the throttle trigger into
the tank. Then push/clip the front edge into the two
clips on the tank with the aid of a combination tool,
for example. Drive in the steel pin from the clutch
side. Use a 2.5 mm/0.1" diameter drift.
3
Then press down the return spring while pressing
the throttle lock forwards/upwards into the retaining
clip in the fuel tank until you hear a click. Release
the return spring in the throttle lock, then press the
lock down onto the tank.
4
Check the operation of the throttle lock by trying to
press the throttle trigger without pressing down the
throttle lock. Also check that the throttle lock and
throttle trigger return freely to their original posi-
tions when released.
B
A
C
B
A
C
A
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18 – English
Hand grip heater on model 346XPG,
351G, 353G –removal
No heating or heating only in front hand grip
•Front hand grip –troubleshooting
1
Remove the three bolts that secure the cover over
the front hand grip. Disconnect the leads from the
switch and generator and measure the resistance of
the hand grip heater, which should be 3–4 ohm.
Replace the front hand grip if the resistance is higher.
2
Reconnect the leads and refit the cover.
3
Push the switch back into place and reconnect the
leads.
4
Bolt the cover back onto the hand grip.
•Generator –troubleshooting
1
Remove the cylinder cover and cover from the
front hand grip. Disconnect the black lead from the
generator and connect a multimeter between it and
a clean area on the cylinder. The multimeter should
show a resistance of 0.9–1.3 ohm. If the reading is
higher or lower, replace the generator, see “Re-
placing the generator”.
2
Reconnect the lead and refit the hand grip cover
and cylinder cover.
•Switch –troubleshooting
1
Carefully free the switch and frame from the front
hand grip using a screwdriver.
2
Disconnect the leads from the switch and connect
a multimeter to it. The meter should read over
1000 ohm when the switch is in the “0” position.
The meter should read no higher than 0.1 ohm with
the switch in the “1” position. Replace the meter if
the readings are outside these limits.
Rear hand grip heater not working
•Rear hand grip heater –troubleshooting
1
Remove the cylinder cover, air filter and cover from
the rear hand grip.
2
Disconnect the red lead from the heater and
connect a multimeter between it and the black
earth lead that is bolted to the bottom of the
carburettor on the clutch side of the saw. The
meter should read 0.7–1.2 ohm. If the reading is
higher replace the heater element.
3
Remove the air filter, throttle pushrod, rubber
diaphragm and carburettor, see “Carburettor –
removal”.
4
Remove the bolt from the plate at the base of the
carburettor to release the lead for the heater
element.
5
Repair instructions
Unscrew the three bolts from the front hand grip
and remove the cover to reveal the leads. Discon-
nect the red lead.
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www.mymowerparts.com

English – 19
Unscrew the two bolts from the right side of the
rear hand grip. Remove the throttle lock and
throttle handle, see “Throttle trigger”. Pull out the
heater element with the leads still connected.
Troubleshooting carburettor heater
(346XPG, 351G, 353G)
Operation
The carburettor temperature is controlled by an
electronic thermostat to eliminate the risk of ice
formation in the carburettor. The thermostat
switches on/off at 12°C/54F. This means that the
saw operator does not need to remember to switch
the carburettor heater on or off.
•Troubleshooting
Front handle heater
Remove the side cover from the handle. Discon-
nect the leads at F and G (see diagram).
Clean the connectors. Turn the switch ”on”.
Measure the resistance between F and G.
The reading should be 4±1 ohms. If not, discon-
nect the lead at O and remove the switch.
Measure the resistance between O and F. The
reading should be 4±1 ohms. If the resistance is
incorrect, replace the front handle.
Disconnect the lead at N and G and measure the
resistance between these points. The reading
should be no higher than 0.1 ohm. If it is too high,
replace the lead.
Switch
Measure the resistance between N and O with the
switch turned off. The reading should be 1 000
ohms or higher.
Repeat the measurement with the switch turned
on. The reading should be no higher than 0.1 ohm.
If it is too high, replace the switch.
6
Repair instructions
Rear handle heater
Measure the resistance between F and Z. It should
be 1 ± 0.5 ohm.
If not, replace the rear handle heater.
Generator
Measure the resistance between G and H. It
should be between 0.3–1.3 ohm.
If not, replace the generator.
Carburettor heater
Disconnect the lead at X and clean the connectors.
Measure the resistance between X and G.
The reading should be between 3–10 ohms. If not,
disconnect the lead at Y and clean the connectors.
Measure the resistance between X and Y, if the
reading is not between 3–7 ohms – replace the
carburettor heater.
O
N
F
G
Z
Y
H
KX
V
3
5
4
1
V
K
O
N
F
G
Z
X
Y
H
5
3
4
1
For Husqvarna Parts Call 606-678-9623 or 606-561-4983
www.mymowerparts.com