Arctic Cat ZR 120, Service Manual

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Troubleshooting Fuel
System
Problem: Carburetor Too Rich (0-1/4 Opening)
Condition Remedy
1. Choke valve will not seat
2. Idle fuel adjuster screw out of adjustment
3. Float/needle jet obstructed — damaged — adjusted incor-
rectly
4. Pilot jet loose
1. Adjust — service — replace choke cable — assembly
2. Adjust idle fuel adjuster screw
3. Remove obstruction — replace needle jet — float
4. Tighten pilot jet
Problem: Carburetor Too Rich (1/4-3/4 Opening)
Condition Remedy
1. Pilot jet too large
2. Float/needle jet obstructed — damaged — adjusted incor-
rectly
3. Main jet loose — too large
4. Primary air passage obstructed
1. Replace pilot jet
2. Remove obstruction — replace needle jet — float
3. Tighten — replace main jet
4. Remove obstruction
Problem: Carburetor Too Rich (3/4-WOT Opening)
Condition Remedy
1. Main jet loose — too large
2. Float/needle jet obstructed — damaged — adjusted incor-
rectly
1. Tighten — replace with smaller main jet
2. Remove obstruction — replace needle jet — float
Problem: Carburetor Too Lean (0-1/4 Opening)
Condition Remedy
1. Choke valve hanging open
2. Pilot jet — outlet obstructed
3. Float/needle jet obstructed — damaged — adjusted incor-
rectly
1. Adjust — service choke cable — valve assembly
2. Remove obstruction
3. Remove obstruction — replace needle jet — float
Problem: Carburetor Too Lean (1/4-3/4 Opening)
Condition Remedy
1. Pilot jet — outlet — main jet obstructed
2. Float/needle jet obstructed — damaged — adjusted incor-
rectly
1. Remove obstruction
2. Remove obstruction — replace needle jet — float
Problem: Carburetor Too Lean (3/4-WOT Opening)
Condition Remedy
1. Main jet obstructed — too small
2. Float/needle jet obstructed — damaged — adjusted incor-
rectly
1. Remove obstruction — replace with larger main jet
2. Remove obstruction — replace needle jet — float
Problem: General Fuel System (Engine Cuts Out at High RPM)
Condition Remedy
1. Fuel delivery inadequate
2. In-line fuel filter obstructed — damaged
3. Gasoline contaminated
4. Gas-tank vent — hose obstructed
1. Repair — replace hose
2. Remove obstruction — replace in-line fuel filter
3. Replace gasoline — de-ice — clean carburetor
4. Remove obstruction — replace vent — hose