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© 2011 ICS- Blount Inc Specifications and pricing are subject to change without notice. P/N 525747 REV12Sep2012
680GC SERVICE MANUAL
CHECK
POSSIBLE CAUSE
REPAIR
The engine runs rough at
all speeds
The engine is overheating.
•
Operator is overworking
the saw.
•
Carburetor mixture is too
lean.
•
Incorrect fuel/oil ratio.
•
Flywheel fins are clogged.
•
Air deflector is missing.
•
Cylinder fins are clogged
Poor acceleration.
•
Dirty or clogged air filter.
•
Clogged fuel filter.
•
Incorrect carburetor tune.
•
Plugged tank breather.
•
Blocked pulse tube.
Uneven idle or engine
may “run away”
•
Air leak at intake boot,
cylinder gasket, or
crankcase gasket.
•
Faulty carburetor
diaphragm.
Diamond chain moves
at idle.
•
Idle speed too high.
•
Broken clutch spring.
Excessive vibration.
YES
•
Damaged shock absorber.
•
Damaged or broken
flywheel fins.
•
Bent crankshaft.
•
Replace shock absorbers
•
Replace flywheel.
•
Replace crankshaft.
•
Adjust idle speed.
•
Replace clutch spring.
YES
•
Inspect air intake boot.
•
Pressure test crankcase.
•
Replace carburetor.
YES
•
Clean or replace the air filter.
•
Replace fuel filter.
•
See Carburetor Tuning section.
•
Repair or replace fuel tank
breather.
•
Replace pulse tube.
YES
•
See Operator’s Manual.
•
See Carburetor Tuning section.
•
See Saw Specifications section.
•
Clean flywheel fins with wire
brush.
•
See Starter Cover section.
•
Clean cylinder fins.
YES
•
Dirty or clogged air filter.
•
Water has been ingested.
•
Loose or dirty spark plug.
•
Clean or replace the air filter.
•
Inspect air intake sysetm for water.
•
Inspect fuel system for water.
•
Tighten, clean, or replace spark
plug.
YES
A dirty air filter is the #1 reason for engine problems.
25. DIAGRAMS
