The Husqvarna 445, 445E and 450E chainsaw service and repair troubleshooting guide will help with the repair and service of a chainsaw not starting or a chainsaw running badly. The carburetor may just need a clean, adjustment or replacing, this guide should help with this. A Service Manual detailing the troubleshooting guide as well as more complete chainsaw repair information is available to download. Also a Parts List, Operator Manual, and carburetor manual are also available to view or download as a PDF which can be read on any device or printed.
Time taken for a medium skilled person to do this is about 30 minutes to 2 hours. The repair fully Covers the following Husqvarna chainsaw models:445, 445 E and 450 E.
Husqvarna 445, 445E and 450E Troubleshooting
The various faults that can affect a chainsaw are divided into four groups. In each group, the likely symptoms are given on the left and possible causes are listed on the right. The most likely faults are given first, and so on.
Starting
|
Difficulty starting |
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 |
|
Carburetor leaking fuel |
Loose or faulty fuel pipe Hole in diaphragm Worn needle valve Needle valve assembly sticking Needle valve set too high Leak in the metering system (air or fuel) Loose cover on the carburetor pump side |
|
Flooding when engine not running |
Worn needle valve set too high Needle valve assembly sticking |
Idling (low rpm)
Idling (low rpm) (cont.)
|
Idles when L screw closed |
Worn needle valve Leaking control diaphragm/cover plate Needle valve assembly sticking Worn needle valve lever Faulty diffuser jet |
|
Idling uneven |
Fuel filter blocked Fuel line blocked Leaking air intake hose (rubber) Loose carburetor mounting bolts Worn throttle valve pivot Loose throttle valve screw Worn throttle valve Needle valve assembly sticking Leak in the metering system (air or fuel) Metering system center knob is worn Hole in diaphragm Leaking control diaphragm/cover plate Crankcase leaking |
|
L screw requires constant adjustment |
Fuel line blocked Needle valve set too high Needle valve assembly sticking Leak in the metering system (air or fuel) Leaking control diaphragm/cover plate Faulty diffuser jets Crankcase leaking |
|
Too much fuel at idling |
Needle valve set too high Needle valve assembly sticking Metering system damaged Worn needle valve Leaking control diaphragm/cover plate The metering system incorrectly assembled |
|
Will not idle |
Adjust L screw Leaking air intake hose (rubber) Loose carburetor 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 |
|
Idling too rich |
Adjust L screw Worn needle valve Needle valve set too high Worn needle valve lever Leaking control diaphragm/cover plate Needle valve assembly sticking |
High rpm
|
Will not run at full throttle |
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 the carburetor pump side Faulty pump diaphragm Leaking air intake hose (rubber) Loose carburetor 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 |
|
Low power |
Adjust H screw Blocked fuel tank vent Blocked fuel filter Impulse channel leaking Impulse channel blocked Loose cover on carburetor pump side Faulty pump diaphragm Blocked air filter Needle valve assembly sticking Leak in the metering system (air or fuel) The metering system incorrectly assembled Loose diaphragm rivet Hole in the diaphragm Leaking control diaphragm/cover plate |
|
Will not “four- stroke” |
Blocked fuel tank vent Blocked fuel filter Fuel line blocked Loose or damaged fuel hose Impulse channel leaking Impulse channel blocked Loose cover on the carburetor pump side Faulty pump diaphragm Leaking air intake hose (rubber) Loose carburetor 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 |
Acceleration och retardation
|
Does not accelerate |
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 the carburetor pump side Faulty pump diaphragm Leaking air intake hose (rubber) Loose carburetor mounting bolts Needle valve set too low Metering system incorrectly assembled Needle valve assembly sticking Faulty diffuser jets Blocked silencer |
|
|
Engine stalls |
Adjust L screw |
|
when throttle |
Adjust H screw |
|
released |
Faulty pump diaphragm |
|
Needle valve set too high |
|
|
Needle valve assembly sticking |
|
|
Faulty diffuser jets |
|
|
Over rich acceleration |
Adjust L screw Adjust H screw |
|
Blocked air filter Faulty pump diaphragm Faulty diffuser jets |
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- Troubleshooting methods
In addition to the faults described in the above table, troubleshooting 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 carburetor
- Pressure testing the decompression valve
- Pressure testing the cylinder
Troubleshooting and fault finding for Husqvarna 445 445e 450e chainsaw