3.50
ENGINE
TROUBLESHOOTING
Engine
Engine Turns Over But Fails to Start
• No fuel
•Dirt in fuel line or filter
• Fuel will not pass through fuel valve
•Fuel pump inoperative/restricted
•Tank vent plugged
•Carb starter circuit
•Engine flooded
•Low compression (high cylinder leakage)
•No spark (Spark plug fouled)
Engine Does Not Turn Over
•Dead battery
• Starter motor does not turn
•Engine seized, rusted, or mechanical failure
Engine Runs But Will Not Idle
•Restricted carburetor pilot system
• Carburetor misadjusted
• Choke not adjusted properly
•Low compression
•Crankcase breather restricted
Engine Idles But Will Not Rev Up
•Spark plug fouled/weak spark
•Broken throttle cable
•Obstruction in air intake
• Air box removed (reinstall all intake components)
•Incorrect or restricted carburetor jetting
•ETC switch limiting speed
•Reverse speed limiter limiting speed
•Carburetor vacuum slide sticking/diaphragm damaged
•Incorrect ignition timing
•Restricted exhaust system
Engine Has Low Power
• Spark plug fouled
• Cylinder, piston, ring, or valve wear or damage (check
compression)
• PVT not operating properly
• Restricted exhaust muffler
•Carburetor vacuum slide sticking/diaphragm damaged
• Dirty carburetor
Piston Failure - Scoring
•Lack of lubrication
•Dirt entering engine through cracks in air filter or ducts
• Engine oil dirty or contaminated
Excessive Smoke and Carbon Buildup
• Excessive piston-to-cylinder clearance
• Wet sumping
• Worn rings, piston, or cylinder
• Worn valves, guides or seals
•Restricted breather
•Air filter dirty or contaminated
Low Compression
•Decompressor stuck
•Cylinder head gasket leak
•No valve clearance or incorrectly adjusted
• Cylinder or piston worn
• Piston rings worn, leaking, broken, or sticking
•Bent valve or stuck valve
• Valve spring broken or weak
•Valve not seating properly (bent or carbon accumulated
on sealing surface)
•Rocker arm sticking
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