Stihl FS 94 Instruction Manual page 15

Condition
Engine running extremely rich, has
no power and a very low maximum
speed
Engine does not start
14
Cause
Cold start device of control valve
sticking or does not return to
original position
No spark
Starter rope not pulled vigorously
enough
– fuel mixture too rich (flooded)
Jet on the
low speed screw L blocked
– no fuel feed
Jet on the
low speed screw L broken – engine
stalls
Remedy
Check and clean the control valve
or replace if necessary
Replace spark plug, check ignition
module/control unit, replace if
necessary
Remove and dry off the spark plug,
pull starter rope several times to
clear combustion chamber, refit
and tighten down the spark plug,
repeat starting procedure
Clean the carburetor or replace if
necessary
Install new carburetor
Series 4149 Powerhead