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8-6
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APPENDIX
Troubleshooting Guide
Engine Doesn’t Start, Starting Difficulty:
Starter motor not rotating:
Neutral switch trouble
Starter motor trouble
Battery voltage low
Relays not contacting or operating
Starter button not contacting
Wiring open or shorted
Ignition switch trouble
Engine stop switch trouble
Fuse blown
Starter motor rotating but engine doesn’t turn
over:
Starter motor clutch trouble
Recoil starter not operating
Recoil starter spring broken
Recoil starter pawl not engaging
Engine won’t turn over:
Valve seizure
Rocker arm seizure
Cylinder, piston seizure
Crankshaft seizure
Connecting rod small end seizure
Connecting rod big end seizure
Transmission gear or bearing seizure
Camshaft seizure
Balancer bearing seizure
No fuel flow:
Fuel tank air vent obstructed
Fuel tap clogged
Fuel line clogged
Float valve clogged
Engine flooded:
Fuel level too high
Float valve worn or stuck open
Starting technique faulty
(when flooded, crank the engine with the throttle
fully opened to allow more air to reach the engine.)
Fuel/air mixture incorrect:
Pilot screw and/or idle adjusting screw maladjusted
Pilot jet, or air passage clogged
Air cleaner clogged, poorly sealed, or missing
Starter jet clogged.
No spark; spark weak:
Spark plug dirty, broken, or maladjusted
Spark plug cap or spark plug lead trouble
Spark plug cap not in good contact
Spark plug incorrect
Pickup coil trouble
CDI unit trouble
Ignition coil trouble
Battery voltage low
Ignition or engine stop switch shorted
Wiring shorted or open
Fuse blown
Compression Low:
Spark plug loose
Cylinder head not sufficiently tightened down
No valve clearance
Cylinder, piston worn
Piston ring bad (worn, weak, broken, or sticking)
Piston ring/groove clearance excessive
Cylinder head gasket damaged
Cylinder head warped
Valve spring broken or weak
Valve not seating properly (valve bent, worn, or
carbon accumulation on the seating surface)
Poor Running at Low Speed:
Spark weak:
Spark plug dirty, broken, or maladjusted
Spark plug cap or Spark plug lead trouble.
Spark plug cap shorted or not in good contact
Spark plug incorrect
CDI unit trouble
Pickup coil trouble
Ignition coil trouble
Battery voltage low
Fuel/air mixture incorrect:
Pilot screw and/or idle adjusting screw maladjusted
Pilot jet, or air passage clogged
Starter plunger stuck open
Air cleaner clogged, poorly sealed, or missing
Fuel level too high or too low
Fuel tank air vent obstructed
Carburetor holder loose
Air cleaner duct loose
Compression low:
Spark plug loose
Cylinder head not sufficiently tightened down
No valve clearance
Cylinder, piston worn
Piston ring bad (worn, weak, broken, or sticking)
Piston ring/groove clearance excessive
Cylinder head gasket damaged
Cylinder head warped
Valve spring broken or weak
Valve not seating properly (valve bent, worn, or
carbon accumulation on the seating surface)
Other:
Carburetor vacuum piston doesn’t slide smoothly
CAUTION
This is not an exhaustive list, giving every possible cause for
each problem listed. It is meant simply as a rough guide to
assist the troubleshooting for some of the more common
difficulties.
Summary of Contents for DL702
Page 1: ... 0 0 FOREWORD INDEX ...
Page 88: ... 7 13 ELECTRICAL SYSTEM Wiring Diagram ...
Page 89: ... 7 14 ELECTRICAL SYSTEM Wiring Diagram ...
Page 90: ... 7 15 ELECTRICAL SYSTEM NOTE ...
