Stihl 020 T Service Manual page 11

Condition
Engine will not idle,
idle speed too high
Engine stalls at idle speed
Engine speed drops quickly under
load - low power
See also 2.2
STIHL 020 T
Cause
Diaphragm gasket leaking
Metering diaphragm damaged or
shrunk
Throttle shutter opened too wide
Idle jet bores or ports
blocked
Idle jet "too rich"
Setting of idle speed
adjusting screw incorrect
- throttle shutter completely
closed
Small plastic plate in valve
jet does not close
Air filter dirty
Tank vent faulty
Leak in fuel line between tank
and fuel pump
Pump diaphragm damaged or
fatigued
Main jet bores or ports
blocked
Fuel pickup body dirty
Fuel strainers dirty
Remedy
Fit new diaphragm gasket
Fit new metering diaphragm
Reset idle speed adjusting screw
by idle speed adjusting screw
correctly
Clean jet bores and ports
with compressed air
Screw down low speed adjusting
screw slightly
(see Carburetor Adjustment)
Set idle speed adjusting
screw correctly
Clean or renew valve jet
Clean air filter
Clean or replace tank vent if
necessary
Seal or renew connections
and fuel line
Fit new pump diaphragm
Clean bores and ports
Clean pickup body, fit new
filter
Clean fuel strainers
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