Stihl MS 661

74 MS 661, MS 661 C-M
8.7.5 Engine stops suddenly
Power tool
in order?
Troubleshooting
completed
– Check fuel system (pickup
body, tank vent, fuel hoses),
b 13.11
– Repair the fuel
system
– Check plug and screw
connections on control unit or
between wiring harness and
switch unit
yes
Fuel system
in order?
Connection
and tightness of
connectors OK?
– Check the plug
connectors, replace wiring
harness and/ or switch unit
if necessary, b 8.3.3,
b 7.10, b 8.5
yes
no
no
Engine stops suddenly
no
yes
– Check start
detection (microswitch,
activating lever) and clean if
necessary
– Replace switch unit,
b 8.5
– Check start detection, wiring
harness, plug and screw
connections, b 8.3.5,
b 8.3.6, b 8.3.3
Mechanically
in order?
– Check the switch unit
and wiring harness and
clean or replace if
necessary, b 8.3.5,
b 8.3.6, b 8.5, b 7.10
yes
no
– Check the solenoid valve,
b 8.3.4
Specified values
obtained?, b 8.3.4
– Install new carburetor,
b 13.4
yes
yes
– Check engine for leaks,
b 6.2
no
no
Specified values
obtained?, b 8.3.6