TOHATSU BFT250A Service Manual page 102

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TROUBLESHOOTING
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 keep sounding?
YES
NO
2. Engine idle speed inspection
Check the idle speed (page 3-22).
Is the idle speed normal?
YES
NO
3. Spark Test
Perform spark test (page 8-4) at all plugs.
Is there weak or no spark?
YES
NO
4. Spark Plug Inspection
Remove and inspect spark plugs.
Is the spark plug wet?
YES
NO
5. Fuel Flow Inspection
Inspect the fuel flow (page 5-113).
Is the fuel flow within specification?
YES
NO
6. Pressure regulator inspection
Inspect the fuel pressure and record it (page 5-111).
Disconnect the pressure regulator vacuum tube.
Inspect the fuel pressure.
Is the fuel pressure higher with the vacuum tube disconnected?
YES
NO
7. Neutral switch inspection
Inspect the neutral switch (page 9-20).
Is the neutral switch normal?
YES
NO
4-10
– Perform alert system/warning system troubleshooting (page 4-18).
– GO TO STEP 2.
– Improperly adjusted idle adjusting screw.
– GO TO STEP 3.
– Perform ignition system troubleshooting (page 8-3).
– GO TO STEP 4.
– • Incorrect spark plug gap
• Incorrect spark plug heat range
• Blocked air cleaner
– GO TO STEP 5.
– GO TO STEP 6.
– • Clogged fuel strainer (Low pressure side) (page 3-27)
• Clogged water separator (page 5-93)
• Clogged or damaged fuel tube
• Faulty fuel pump (Low pressure side)
• Clogged vapor separator air vent tube or filter
• Clogged fuel feed hose
• Clogged fuel strainer (High pressure side) (page 5-106)
• Faulty vapor separator (page 5-115)
• Faulty fuel pump (high pressure side)
– GO TO STEP 7.
– Faulty pressure regulator.
– GO TO STEP 8.
– Replace the neutral switch with a new one and recheck.