Troubleshooting - Honda CRF50F 2004 Service & Repair Manual

FUEL SYSTEM
TROUBLESHOOTING
Engine cranks but won't st art
• Too much fuel getting to the engine
- Air cleaner clogged
- Flooded carburetor
• Intake air leak
• Fuel contaminated/deteriorated
• No fue l to carbu retor
- Fuel strainer clogged
- Fuel hose clogged
- Float level misadjusled
- Fuel tank breather hose clogged
Lean mixture
• Fuel jets clogged
• Float valve faully
• Float level too low
• Fuel line restricted
• Carburetor air vent hose clogged
• Clogged fuel strainer screen
• Intake air leak
• Throttle valve faulty
Rich mixture
• Choke lever in CLOSE position
• Float valve faulty
• Float level 100 high
• Air jets clogged
• Air cleaner element contami nated
• Flooded carburetor
Engine stalls, hard to start. idles roughly
• Fuel line restricted
• Ignition malfu nction
• Fuel mixture too lean/rich
• Fuel contaminated/deteri orated
• Intake air leak
• Idle speed misadjusted
• Float level misadjusted
• Fuel tank breather hose clogged
• Air screw misadjusted
• Slow circuit clogged
Afterburn when engine braking is used
• Lean mixture in slow circuit
Backfiring or misfiring during acceleration
• Ignition syst em malfunction
• Fuel mixture too lean
Poor performance (driveability) and poor fuel economy
• Fuel system clogged
• Ignition system malfunction
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