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9928491 R04 - 2017-2018 RZR XP Turbo / XP4 Turbo Service Manual
© Copyright Polaris Industries Inc.
EFI DIAGNOSTICS
FUEL SYSTEM 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.
• No fuel in tank
• Restricted tank vent, or routed improperly
• Fuel lines or fuel injectors restricted
• Fuel filter plugged
• Fuel pump inoperative
• Air leak in system
• Intake air leak (throttle shaft, intake ducts, air box
cover)
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.
• Air intake restricted (inspect intake duct)
• Air filter dirty/plugged
• Poor fuel quality (old fuel)
• Fouled spark plug
• Injector failure
Idle Too High (if > 1400 RPM when warm)
• Throttle stop screw tampering
• Throttle cable sticking, improperly adjusted, routed
incorrectly
• Faulty electrical connection
Idle Too Low (if < 1100 RPM when warm)
• Plugged air filter
• Leaking injector (rich condition)
• Belt dragging
• Throttle stop screw tampering
Erratic Idle
• Throttle cable incorrectly adjusted
• Air Leaks, dirty injector
• TMAP damaged (check with Digital Wrench®)
• Tight valves (low compression or high leakdown)
• Ignition timing incorrect
• Belt dragging
• Dirty air filter
• High percentage of cylinder leakdown (worn engine)
• Low compression (worn engine)
• Spark plug(s) fouled
• Spark plug wires loose or worn
• Faulty electrical connection
EFI / FUEL SYSTEM
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