Engine Does Not Start; Engine Overheats; Troubleshooting Engine (2-Stroke Carbureted) - Arctic Cat Sno Pro 120 Service Manual

Troubleshooting Engine
(2-Stroke Carbureted)
Problem: Engine Does Not Start (No Spark at Spark Plugs)
Condition
1. Ignition switch malfunctioning — not in RUN position
2. Wiring harness shorting — connection poor
3. Emergency stop switch knob in DOWN position —
malfunctioning
4. Throttle/ignition monitor switch adjusted too tight —
malfunctioning
5. Carburetor safety switches adjusted incorrectly —
malfunctioning
6. Spark plugs fouled — damaged
7. Spark-plug caps damaged — leaking — shorting
8. High tension wires/coil loose — grounded — faulty
9. CDI unit faulty
10. Charge coil (1) faulty
11. Charge coil (2) faulty
12. Flywheel magnets weak
13. Flywheel key sheared
Problem: Engine Does Not Start (No Fuel at Cylinders)
Condition
1. Gas tank empty
2. Shut-off valve closed
3. Fuel hose broken — pinched
4. Gas-tank vent — hose obstructed
5. In-line fuel filter obstructed — damaged
6. Fuel pump malfunctioning — faulty
7. Impulse hose cracked — broken — pinched — discon-
nected
8. Carburetors adjusted incorrectly — dirty — damaged
9. Primary compression (crankcase) absent
Problem: Engine Overheats
Condition
1. Spark plug heat range too hot
2. Coolant low — absent
3. Carburetors adjusted incorrectly — jetted incorrectly —
dirty
4. Carburetor-to-cylinder air leak
5. Heat exchangers no snow for cooling
6. Rings/grooves carboned
7. Exhaust ports obstructed
8. Muffler obstructed
9. Gas/air mixture incorrect
10. Oil-injection pump malfunctioning — adjusted incorrectly
11. Primary compression (crankcase) low — absent
12. Ignition timing adjusted incorrectly
13. Gasoline octane too low
14. Water pump — thermostat damaged — faulty
Remedy
1. Replace ignition switch — turn switch to RUN position
2. Repair — connect — replace wiring harness
3. Move knob to UP position — replace throttle switch
4. Adjust (loosen) throttle cable — replace throttle switch
5. Adjust — replace carburetor safety switches
6. Clean — gap — replace spark plugs
7. Replace spark-plug caps
8. Service — replace high tension wires/coil
9. Replace CDI unit
10. Replace coil
11. Replace coil
12. Replace flywheel
13. Replace key
Remedy
1. Fill tank
2. Open shut-off valve
3. Replace — service hose
4. Remove obstruction — replace vent — hose
5. Remove obstruction — replace in-line fuel filter
6. Replace — repair — clean fuel pump
7. Replace — connect impulse hose
8. Troubleshoot — clean — replace carburetors
9. Repair — replace damaged — worn engine components
Remedy
1. Install lower heat-range spark plugs
2. Add coolant
3. Troubleshoot — clean carburetors — jet correctly
4. Replace — repair gaskets — intake flanges — service
intake ports
5. Select new trail — install ice studs to chew up hard packed
snow and ice
6. Clean — replace rings — pistons
7. Remove obstruction
8. Remove obstruction
9. Replace jets — adjust jet needle E-clip position
10. Replace — bleed — adjust oil-injection pump
11. Repair — replace damaged — worn engine components
12. Time ignition
13. Use 87 minimum octane gasoline
14. Replace — rebuild water pump — replace thermostat
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