Stihl MS 390 User Manual

74 MS 290, MS 310, MS 390
Correct operation of the carburetor
is only possible if atmospheric
pressure and internal fuel tank
pressure are equal at all times. This
is ensured by the tank vent.
In the event of trouble with the
carburetor or the fuel supply
system, always check and clean the
tank vent.
Check operation by performing
vacuum test on the tank via the fuel
hose.
– Remove the carburetor box
cover, b 11.1
: Use a suitable tool to pry the tank
vent off the nipple on the fuel
tank.
: Take the tank vent out of its seat
VA
209RA055
in the handle housing (arrow).
: Use a 3 mm drift to push the
grub screws (1) out of the vent
hose (2).
VA
209RA056
2
1
1
Clean all components in standard
solvent-based degreasant
containing no chlorinated or
halogenated hydrocarbons,
b 13.
Install in the reverse sequence.
: Use a 3 mm drift to push the
grub screws (1) into the vent
hose (2).
Pay special attention to correct
installed position of lower grub
screw. Dimension ’a’ should be
about 18 mm.
VA
209RA057
a
Check correct installed position of
tank vent in the handle housing.
Install all other parts in the reverse
sequence.
11.5 Tank Vent 11.5.1 Machines up to 2002

Stihl MS 390 Specifications

General

Engine Displacement	64.1 cc
Chain Pitch	3/8"
Weight	6.2 kg
Guide Bar Lengths	40 to 50 cm
Fuel Capacity	0.68 l (23.0 oz)