Troubleshooting - Polaris SCRAMBLER 50 Service Manual

FUEL SYSTEM/CARBURETION

TROUBLESHOOTING

FUEL STARVATION/LEAN MIXTURE
Symptoms: Hard start or no start, bog, backfire,
popping through intake / exhaust, hesitation,
detonation, low power, spark plug erosion, engine
runs hot, surging, high idle, idle speed erratic.
G
No fuel in tank
G Restricted tank vent, or routed
improperly
G Fuel lines or fuel valve restricted
G Fuel filter plugged
G Carburetor vent line(s) restricted
G Plugged or restricted inlet needle
and seat screen or inlet passage
G
Clogged jets or passages
G
Float stuck, holding inlet needle
closed or inlet needle stuck
G Float level too low
G Intake air leak ( crankcase seal
throttle shaft, intake ducts, airbox
or air cleaner cover)
G
Jet needle position incorrect
G
Incorrect pilot screw adjustment
RICH MIXTURE
Symptoms: Fouls spark plugs, black, sooty exhaust
smoke, rough idle, poor fuel economy, engine runs
rough/ misses, poor performance, bog, engine loads
up, backfire.
G
Air intake restricted (inspect intake
duct)
G Air filter dirty/plugged
G Electric choke inoperative
G Incorrect pilot air/fuel screw
adjustment
G Faulty inlet needle and seat
G
Faulty inlet needle seat O-Ring
G
Float level too high
G
Poor fuel quality (old fuel)
G
Loose jets
G Worn jet needle/needle jet or other
carburetor parts
G
Dirty carburetor (air bleed
passages or jets)
G
Fouled spark plug
POOR IDLE
Symptoms: Idle too high.
G Idle adjusted improperly/idle
mixture screw damaged
G Sticky throttle valve
G Throttle cable sticking, improperly
adjusted, routed incorrectly
IDLE TOO LOW
G Idle speed set incorrectly
G
Idle mixture screw misadjusted or
damaged
G
CVT system dragging
G Ignition timing incorrect
G Worn jet needle/needle jet
ERRATIC IDLE
G
Choke not working properly
G
Throttle cable incorrectly adjusted
G Air leaks, dirty carburetor passages
(pilot circuit)
G
Pilot mixture screw damaged or
adjusted incorrectly
G
Ignition timing incorrect
G Belt dragging
G Dirty air cleaner
G Engine worn
G Spark plug fouled
G
Idle speed set incorrectly (speed
limiter)
G
Worn jet needle/needle jet
3.13