FUEL SYSTEM/CARBURETION
4.14
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
Fuel pump inoperative
G
Air leak at impulse line
G
Restricted impulse line (kinked,
pinched)
G
Intake air leak (throttle shaft, intake
ducts, airbox or air cleaner cover)
G
Ruptured vacuum slide diaphragm,
Vacuum slide stuck closed or sticky
G
Improper spring
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
Choke plunger sticking, incorrectly
adjusted choke
G
Choke cable binding or improperly
routed
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
Weak or damaged vacuum piston
return spring
G
Fouled spark plug
POOR IDLE
Idle Too High
G
Idle adjusted improperly/idle
mixture screw damaged
G
Sticky vacuum slide
G
Throttle cable sticking, improperly
adjusted, routed incorrectly
G
Choke cable sticking, improperly
adjusted, routed incorrectly
G
Plugged or restricted idle jet
Idle Too Low
G
Choke cable bending or incorrectly
adjusted
G
Idle speed set incorrectly
G
Idle mixture screw misadjusted or
damaged
G
Belt dragging
G
Ignition timing incorrect
G
Worn jet needle/needle jet
G
Plugged or restricted idle jet
Erratic Idle
G
Choke cable bending or incorrectly
adjusted
G
Throttle cable incorrectly adjusted
G
Air leaks, dirty carburetor passages
(pilot circuit)
G
Pilot mixture screw damaged or
adjusted incorrectly
G
Tight valves
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
G
Plugged or restricted idle jet
Summary of Contents for SPORTSMAN 400 2003
Page 1: ...2003 SPORTSMAN 400 500 SERVICE MANUAL PN 9918065 The Way Out ...
Page 5: ......
Page 51: ...MAINTENANCE 2 32 NOTES ...
Page 71: ...ENGINE 3 20 CYLINDER HEAD EXPLODED VIEW EH50PL A EH50PL ...
Page 131: ...BODY STEERING SUSPENSION 5 12 NOTES ...
Page 165: ...CLUTCH 6 34 NOTES ...
Page 193: ...FINAL DRIVE 7 28 NOTES ...
Page 217: ...TRANSMISSION 8 24 NOTES ...
Page 239: ...BRAKES 9 22 ...
Page 274: ...PN 9918065 Printed in USA ...