TOHATSU BFT75A Service Manual page 119

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TROUBLESHOOTING
ENGINE DOES NOT RUN SMOOTHLY OR THE ENGINE STALLS DURING
DECELERATION
ENGINE SPEED IS NOT STABLE DURING IDLE AND TROLLING
1. Alert system inspection
Turn the combination switch ON.
Check the warning buzzer sound.
Does the warning buzzer sound twice and then stop?
YES
NO
2. Engine idle speed inspection
Adjust by turning the idle adjusting screw in or out (page 3-20).
Is the idle speed normal?
YES
NO
3. Spark plug inspection
Remove and inspect the spark plugs.
Is the spark plug wet?
YES
NO
4. Intake air leak inspection
Check for secondary air in the system.
Is there an air leak?
YES
NO
5. Fuel Flow Inspection
Inspect the fuel flow (page 5-99)
Is the fuel flow within specification?
YES
NO
6. Pressure regulator inspection
Check the fuel pressure and record it (page 5-97)
Disconnect the pressure regulator vacuum tube.
Check the fuel pressure.
Is the fuel pressure higher with the vacuum tube disconnected?
YES
NO
4-6
– GO TO STEP 2.
– Perform alert system/warning system troubleshooting (page 4-16).
– Improperly adjusted idle adjusting screw.
– GO TO STEP 3.
– • Incorrect spark plug heat range
• Incorrect spark plug gap
• Clogged between the silencer and cylinder head
• Improper vapor separator float height
– GO TO STEP 4.
– • Loose IAC valve and/or throttle body mounting bolt
• Leaking or damaged throttle body and/or IAC valve gasket
• Loose intake manifold mounting bolt
• Leaking or damaged intake manifold seal ring
• Loose fuel line mounting bolts
• Leaking or damaged fuel injector seal ring
– GO TO STEP 5.
– GO TO STEP 6.
– • Clogged or damaged fuel tube
• Clogged fuel strainer (Low pressure side)
• Clogged water separator
• Clogged fuel strainer (Low pressure side)
• Clogged vapor separator air vent tube or filter
• Faulty vapor separator
• Clogged or damaged fuel feed hose
• Clogged fuel strainer (High pressure side)
• Faulty fuel pump (High pressure side)
– GO TO STEP 7.
– • Clogged pressure regulator vacuum tube
• Faulty pressure regulator