Troubleshooting Of The Piston; Pressure Testing Of The Carburettor - Husqvarna 565 Workshop Manual

Troubleshooting

19.2 Troubleshooting of the piston

Score marks in
the piston (A).
Carbon build-up (B).
Piston ring
breakage.
19.3 Pressure testing of the
carburettor
Pressure testing should be carried out with the carburet-
tor fully assembled. Testing should always be carried out
after the carburettor has been repaired, but a test can
also be made for troubleshooting before dismantling.
Option 1
Study figure 3 and carry out the check as follows:
1. Connect the pressure tester to the carburettor fuel
inlet.
2. Submerge the carburettor into a container with
water.
3. Pump up the pressure to 20 kPa.
4. No leakage is permitted. If a leakage occurs refer to
the table below.
Option 2
1. Plug the connections to the fuel inlet.
2. Create a vacuum to the purge nipple on the
carburettor. No leakage is permitted. In the case of
leakage, leakage spray can be used even if it is
difficult. Try and identify where the spray is absorbed.
It can be used to show leakages in main jets, idling
needles, measuring cover gaskets and measuring
diaphragms, and autotune gaskets.
Leak in
Diffuser jets
Leak in the impulse pipe
Ventilation hole on the
metering unit.
Incorrect carburettor setting.
Too high maxspeed.
Too low octane fuel.
Too little or incorrect oil in the
fuel.
Incorrect carburettor setting.
Too low maxspeed.
Too much or incorrect oil in the
fuel.
Excessive engine speed.
Piston ring worn out.
Oversized piston ring groove.
Fault with
Needle valve
Pump membrane
Control membrane
A
Fig. 2
Fig. 3
B
English - 53