Husqvarna T540 XP Workshop Manual page 45

6. Fit the control diaphragm (R) with gasket and
cover (Q) with the bracket for the connector
above the metering unit. See Figure 50.
7. Do a pressure test.
8. See figure 46 on how to assemble the
AutoTune AB unit with gasket.
Note! When replacing the AutoTune unit or car- Note! When replacing the AutoTune unit or car-
burettor with an AutoTune unit, the unit must
first be programmed before it can be used.
Refer to the local support page or
separate instruction for more information.
Pressure testing the carburettor
Pressure testing should be carried out with the
carburettor fully assembled. The test must always
be done after the carburettor has been repaired,
but can also be carried out when troubleshooting
before the carburettor is taken apart.
Test 1
See Figure 51 and carry out the following check:
1
Connect pressure tester to the carburettor fuel inlet.
2
Lower the carburettor into a beaker of water.
3
Pump up the pressure to 20 kPa.
4
No leakage is permitted. If a leakage occurs refer
to the table below.
Leak in
Diffuser jets
Leak in the impulse pipe
Ventilation hole above
metering unit
Test 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 it
if is difficult. Try and identify where the spray is
sucked in. It can be used to show leakages in main
jets, idling needles, measuring cover gaskets and
measuring diaphragms, and AutoTune gasket.
Fault with
Needle valve
Pump diaphragm
Control diaphragm
Fig 50
Fig 51
Repair instructions
45
English –