FUEL SYSTEM
TROUBLESHOOTING
Engine cranks but won't start
• No fuel in tank
• No fuel to carburetor
- Clogged fuel strainer
- Clogged fuel line
- Clogged fuel tank breather hose
• Too much fuel getting to the engine
- Clogged air cleaner
- Flooded carburetor
• Intake air leak
• Contaminated/deteriorated fuel
- Clogged jets
• Clogged starting enrichment (SE) valve circuit
• Improper choke operation
• Improper throttle operation
• No spark at plug (faulty ignition system - See page 19-4)
Lean mixture
• Clogged fuel jets
• Faulty float valve
• Float level too low
• Restricted fuel line
• Clogged carburetor air vent hose
• Restricted fuel tank breather hose
• Intake air leak
• Faulty vacuum piston
• Faulty throttle valve
Rich mixture
• SE valve open
• Clogged air jets
• Faulty float valve
• Float level too high
• Dirty air cleaner
• Worn jet needle or needle jet
• Faulty vacuum piston
Engine stalls, hard to start, rough idling
• Restricted fuel line
• Fuel mixture too lean/rich
• Contaminated/deteriorated fuel
- Clogged jets
• Intake air leak
• Misadjusted idle speed
• Misadjusted pilot screw
• Restricted fuel tank breather hose
• Clogged air cleaner
• Clogged slow circuit
• Clogged SE valve circuit
• Faulty ignition system (page 19-4)
Afterburn when engine braking is used
• Lean mixture in slow circuit
• Faulty air cut-off valve
• Faulty ignition system (page 19-4)
Backfiring or misfiring during acceleration
• Lean mixture
• Faulty ignition system (page 19-4)
Poor performance (driveability) and poor fuel economy
• Clogged fuel system
• Faulty ignition system (page 19-4)
6-4
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