Yamaha EF1000iS, Service Manual

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6-5
ENGINE
TRBL
ENGINE SPEED IS UNEVEN
Check fuel level.
SUFFICIENT INSUFFICIENT
Add.
Check if fuel is deteriorated.
GOOD NO GOOD Replace fuel.
Check if fuel tank cap is clogged.
GOOD NO GOOD Replace.
Check if fuel cock is clogged.
GOOD NO GOOD
Clean.
Check fuel pump operation.
GOOD NO GOOD
Replace.
Check spark plug for dirt and check spark plug gap.
GOOD NO GOOD
Clean, adjust or replace.
While the engine is operating, pull the choke knob
approximately 1/3 to 1/2 way out, and then check the
engine operating condition.
STABLE UNSTABLE
Resurface or replace.
Check for air suction due to a damaged throttle shaft
seal, carburetor joint, or gasket.
GOOD NO GOOD
Disassemble or replace.
Check if slow or main passages such as, the pilot jet
and main jet, in carburetor are clogged.
GOOD NO GOOD
Disassemble or clean.
Check valve face and valve seat for wear.
GOOD NO GOOD
Resurface or replace.
Check if there is seizure or wear on piston, piston ring,
or cylinder.
GOOD
SEIZURE OR
WEAR
Rebore or replace.
Check the condition of the throttle control system.
Refer to “THROTTLE CONTROL SYSTEM”.
Check valve clearance.
GOOD OUT OF SPECIFICATION Adjust.
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