Stihl BT 45 Manual page 10

4.3 Fuel System
Condition
Engine stalls at idle speed
Engine speed drops quickly under
load – low power
Engine will not idle,
idle speed too high
BT 45
Cause
Idle jet bores or ports blocked
Idle jet too rich
Setting of idle speed screw
incorrect – throttle shutter
completely closed
Air filter plugged
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
Throttle shutter opened too wide by
idle speed screw
Remedy
Clean jet bores and ports and blow
clear with compressed air
Screw down low speed screw
slightly (see Adjusting the
Carburetor)
Reset idle speed screw correctly
Clean the air filter or replace if
necessary
Clean the tank vent or replace if
necessary
Seal or renew connections and fuel
line
Fit new pump diaphragm
Clean the bores and ports
Install new pickup body
Reset idle speed screw correctly
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