TOHATSU BFT115A Service Manual page 99

ENGINE SPEED IS UNSTABLE 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 – Perform alert system/warning system troubleshooting (page 4-17).
NO – GO TO STEP 2.
2. Engine idle speed inspection
Adjust by turning the idle adjusting screw in or out (page 3-13).
Does the engine speed and/trolling speed become normal?
YES – Improper original idle adjusting screw adjustment
NO – GO TO STEP 3.
3. Spark Test
Perform the spark test with each ignition coil (page 8-4).
Is there normal spark?
YES – GO TO STEP 4.
NO – Perform ignition system troubleshooting (page 8-3).
4. Spark Plug Inspection
Remove and inspect the spark plugs.
Is the spark plug wet?
YES – • Incorrect spark plug heat range
• Incorrect spark plug gap
• Restriction or blockage between the silencer case and cylinder head
• Improper vapor separator float height
NO – GO TO STEP 5.
5. Fuel Flow Inspection
Inspect the fuel flow (page 5-130).
Is the fuel flow within specification?
YES – GO TO STEP 6.
NO – • Clogged, bent or damaged fuel tube
• Clogged fuel strainer (Low pressure side) (page 3-24)
• Clogged water separator (page 3-24)
• Faulty fuel pump (Low pressure side)
• Clogged vapor separator air vent tube or filter
• Faulty vapor separator (page 5-133)
• Clogged, bent or damaged fuel feed hose
• Clogged fuel strainer (High pressure side) (page 3-26)
• Faulty fuel pump (high pressure side)
6. Pressure regulator inspection
Check the fuel pressure and record it (page 5-129).
Disconnect the pressure regulator control tube.
Check the fuel pressure.
Is the fuel pressure higher with the control tube disconnected?
YES – GO TO STEP 7.
NO – Faulty pressure regulator
7. Neutral switch inspection
Inspect the neutral switch (page 10-19).
Is the neutral switch normal?
YES – GO TO STEP 8.
NO – Replace the neutral switch with a new one and recheck.
TROUBLESHOOTING
4-9