OTHER OBSERVATION |
POSSIBLE CAUSE |
REMEDY |
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• Water in fuel reservoir |
• Flush reservoir and refill with fresh gas |
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• Mechanical engine failure |
• Check cylinder compression
• Check for crankcase leaks
• Check starting system |
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• Spark plug faulty, fouled or worn out |
• Check spark plug condition |
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• Low fuel pressure
(RFI and DI models) |
• Check fuel pump operation. Refer to
ENGINE MANAGEMENT
• Check fuel pressure regulator. Refer to
ENGINE MANAGEMENT |
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• Low air pressure (DI models) |
• Check air compressor system. Refer to
ENGINE MANAGEMENT
• Check RAVE valve for leaks |
ENGINE STARTS BUT RUNS ONLY AT IDLE SPEED |
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• DI models: The DI system is in limp
home mode. |
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• Refer to section ENGINE and check
the fault codes in the MPEM |
ENGINE MISFIRES, RUNS IRREGULARLY |
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• Fouled, defective, worn spark plugs
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• Check/verify heat range/gap/replace
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• Faulty MPEM |
• Check, refer to section ELECTRICAL
SYSTEM or ENGINE MANAGEMENT
on RFI and DI models |
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• Faulty ignition module
(if so equipped) |
• Check, refer to ELECTRICAL SYSTEM |
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• Sheared flywheel key |
• Check timing mark, refer to section
ELECTRICAL SYSTEM |
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• Too much oil supplied to engine |
• Adjust oil injection pump |
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• Bad ignition ground wiring |
• Check wiring condition and proper
grounding of ignition coil |
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• Faulty ignition coil, ignition generatorcoil, trigger coil (if so equipped) orbad connector |
• Check coil. Refer to ELECTRICAL SYSTEM
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• Low fuel level
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• Check/refill
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• Low fuel pressure
(RFI and DI models) |
• Check pump, regulator, injectors and
hose pinchers or if filter is plugged.
Replace if necessary |
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• Stale or water fouled fuel |
• Check/siphon and refill |
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• Fuel filter dirty or restricted |
• Check/clean/replace |
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• Carburetion dirty or out of adjustment
(carburetor models) |
• Check/clean/adjust, refer to section
FUEL SYSTEM |
Lean fuel mixture
Dry spark plug (exceptwhen water fouled) |
• Clogged fuel injectors
(RFI and DI models) |
• Remove and clean fuel injectors |
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• Clogged direct injectors
(DI models) |
• Remove and clean direct injectors |
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• Defective sensor or MPEM
(RFI and DI models) |
• Check faulty codes in MPEM
memory, refer to section ENGINE
MANAGEMENT |
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• Leaking crankshaft seal(s) or intake
(carburetor models) |
• Pressure check engine, refer to section
ENGINE |
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• Restricted fuel valve
(carburetor models) |
• Check/replace |
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• Loose carburetor (carburetor models) |
• Tighten carburetors |
Rich fuel mixture Fouled spark plug |
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Partially closed choke (carburetor models) |
Check/adjust choke cable |
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Flame arrester dirty or restricted (if so equipped) |
Check/replace |
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Carburetor adjustment (carburetor models) |
Check/adjust, refer to section FUEL SYSTEM |
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Loose main jet (carburetor models) |
Check, refer to section FUEL SYSTEM |
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Improper air/fuel rail pressure (DI models) |
Check pressures, refer to ENGINE MANAGEMENT |
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Fuel injector(s) (RFI and DI models) |
Remove and replace fuel injector(s), refer to section ENGINE MANAGEMENT |
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Direct injector(s) (DI models) |
Remove and replace direct injector(s), refer to section ENGINE MANAGEMENT |
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Defective sensor or MPEM (RFI and DI models) |
Check faulty codes in MPEM memory, refer to section ENGINE MANAGEMENT |
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Rotary valve shaft seal leaking (if so equipped) |
Check/replace, refer to ENGINE |
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Damaged reed valve (if so equipped) |
Check, refer to Bottom End in ENGINE SECTION |
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Leaking crankshaft seal(s) or intake (DI models) |
Pressure check engine, refer to section ENGINE |
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Leak in RAVE valve system (DI models) |
Check, refer to ENGINE MANAGEMENT |
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Oil injection pump adjustment |
Check/adjust, refer to section LUBRICATION SYSTEM |
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Worn needles and seals (carburetor models) |
Check, refer to section FUEL SYSTEM |
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Excessive rotary valve clearance (if so equipped) |
Check, refer to ENGINE |
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Fuel pressure and/or air pressure fluctuating (DI models) |
Inspect fuel and air pressure regulators. Refer to ENGINE MANAGEMENT |
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High fuel pressure (RFI and DI models) |
Check pump, regulator, injectors, hose pinchers or if filter is plugged. Replace if necessary |
Start but run poorly |
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- RFI and DI models: Check spark plug condition, check fault codes in the MPEM memory, check fuel pressure, check RAVE valves operation
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- Check, refer to section ENGINE MANAGEMENT. If some work has been performed on the unit, make sure injector wire connectors were not mixed. Refer to the wiring diagram for wire colors and positions
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Also fuel injection misinjecting |
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- DI models: Bent or missing tooth on encoder wheel
- RFI models: Bent or missing tooth on trigger wheel
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- Check, refer to ENGINE MANAGEMENT under Component inspection and adjustment
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Difficult to start |
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- Incorrect rotary valve timing (if so equipped)
- Excessive rotary valve clearance (if so equipped)
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- Check/adjust, refer to ENGINE
- Check, refer to ENGINE
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ENGINE CONTINUALLY BACKFIRES
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| Weak spark |
• Fouled, defective spark plugs |
• Clean/replace |
| • Malfunction of rev limiter in MPEM |
• Clean/replace, refer to section
ELECTRICAL SYSTEM |
Spark plugs |
• Spark plug leads or wiring reversed |
• Check with wiring diagram |
| Ignition timing/TDC setting |
• Incorrect setting |
• Check/reset, refer to section
ELECTRICAL SYSTEM |
| • Sheared flywheel key |
• Check/replace, refer to sections
ELECTRICAL SYSTEM and ENGINE |
Rotary valve
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• Incorrect timing |
• Check/reset, refer to ENGINE |
Carburetor
(if so equipped) |
• Carburetion too lean |
• Check/adjust, refer to section FUEL
SYSTEM |
Engine |
• Intake leak/crankshaft seal failure
(carburetor models) |
• Pressure check engine, refer to section
ENGINE |
ENGINE DETONATION OR PINGIN |
Ignition |
• Timing too far advanced |
• Check/reset |
| • Spark plug heat range too high |
• Check/change to correct range |
Engine temperture |
• Engine overheats |
• Check, see engine overheats |
| • Fuel octane too low of poor quality |
• Use good quality fuel |
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