
© 2017 ICS- Blount Inc Specifications and pricing are subject to change without notice. P/N 598000 REV072717
74
680ES SERVICE MANUAL
CHECK
POSSIBLE CAUSE
REPAIR
The engine
runs rough at all
speeds
The engine is
overheating
•
Operator is overworking
the power cutter.
•
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
•
Damaged shock
absorber.
•
Damaged or broken
flywheel fins.
•
Bent crankshaft.
•
Replace shock absorbers
•
Replace flywheel.
•
Replace crankshaft.
•
Adjust idle speed.
•
Replace clutch spring.
•
Inspect air intake boot.
•
Pressure test crankcase.
•
Replace carburetor.
•
Clean or replace the air
filter.
•
Replace fuel filter.
•
See Carburetor Tuning
section.
•
Repair or replace fuel tank
breather.
•
Replace pulse tube.
•
See Operator’s Manual.
•
See Carburetor Tuning
section.
•
See Power Cutter
Specifications section.
•
Clean flywheel fins with wire
brush.
•
See Starter Cover section.
•
Clean cylinder fins.
•
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
YES
YES
YES
YES
YES