Polaris SPORTSMAN 400 2003 Service Manual page 105

ENGINE
S Cylinder head gasket leak
S
No valve clearance
adjusted
S
Cylinder or piston worn
S
Piston rings worn, leaking, broken, or
sticking
S
Bent valve or stuck valve
S
Valve spring broken or weak
S Valve not seating properly (bent or
carbon accumulated on sealing surface)
S Rocker arm sticking
Backfiring
S
ETC or speed limiter system malfunction
S
Fouled spark plug or incorrect plug or
plug gap
S Carburetion faulty - lean condition
S Exhaust system air leaks
S Ignition system faulty:
Spark plug cap cracked/broken
Ignition coil faulty
Ignition or kill switch circuit faulty
Ignition timing incorrect
Sheared flywheel key
S
Poor connections in ignition system
S System wiring wet
S Valve sticking
S Air leaks in intake
S
Lean condition
COOLING SYSTEM
TROUBLESHOOTING
Overheating
S
Low coolant level
S Air in cooling system
S Wrong type of coolant
S Faulty pressure cap or system leaks
S Restricted system (mud or debris in
radiator fins or restriction to air flow,
passages blocked in radiator, lines,
pump, or water jacket)
S Lean mixture (restricted jets, vents, fuel
pump or fuel valve)
S Fuel pump output weak
S Restricted radiator (internally or cooling
fins)
S
Water pump failure
S
Cooling system restriction
S Cooling fan inoperative or turning too
slowly (perform current draw test)
3.54
or incorrectly
Temperature Too Low
Leak at Water Pump Weep Hole
S Ignition timing misadjusted
S Low oil level
S
Spark plug incorrect heat range
S
Faulty hot light circuit
S Thermostat stuck closed or not opening
completely
S Thermostat stuck open
S Faulty water pump mechanical seal
(coolant leak)
S
Faulty pump shaft oil seal (oil leak)