Stihl MS 390 User Manual

70 MS 290, MS 310, MS 390
The diaphragm material as well as
the inlet and outlet valves are
subjected to continuous alternating
stresses and eventually show signs
of fatigue, i.e. the diaphragm
distorts and swells and has to be
replaced.
: Check fuel strainer (1) for
contamination and damage. If
necessary, use a needle to take it
out of the carburetor and clean or
replace.
Install in the reverse sequence.
VA
212RA167
1
: Fit the diaphragm and gasket on
the carburetor body so that the
tabs (arrow) point toward the
connector (1).
– Place the end cover on the
carburetor body.
VA
212RA168
1
The pump diaphragm, gasket and
end cover are held in position by
integrally cast pegs.
– Fit the screw and tighten it down
firmly, b 3.5
Install all other parts in the reverse
sequence.

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)