TOHATSU BFT250A Service Manual page 95

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6. Spark Plug Inspection
Remove and inspect spark plugs.
Is the spark plug wet?
YES
NO
7. Vapor separator inspection
Loosen the vapor separator drain screw and check whether fuel flows out.
Does the fuel flow properly?
YES
NO
8. Fuel Pump Inspection
You should hear the pump hum when the combination switch is turned "ON".
Is the hum heard?
YES
NO
9. Fuel Flow Inspection
Inspect the fuel flow (page 5-113).
Is the fuel flow within specification?
YES
NO
10. Fuel injector inspection
Inspect the fuel injector (page 5-116).
Is the fuel injector normal?
YES
NO
11. Cylinder Compression
Check the cylinder compression (page 14-33).
Is the compression low?
YES
NO
12. IAC valve inspection
Replace the IAC valve with a new one and start the engine.
Engine starts?
YES
NO
– • Incorrect spark plug heat range
• Incorrect spark plug gap
• Restriction or blockage between the cooling fan cover and cylinder head
• Improper vapor separator float height
– GO TO STEP 7.
– GO TO STEP 8.
– • Closed fuel tank vent knob
• Faulty primer bulb
• Clogged or damaged fuel tube
• Clogged water separator (page 5-93)
• Clogged fuel strainer (Low pressure side) (page 3-27)
• Faulty fuel pump (Low pressure side)
• Clogged vapor separator air vent tube or filter
• Faulty vapor separator (page 5-115)
– GO TO STEP 9.
– Perform fuel pump system inspection (page 5-114)
– GO TO STEP 10.
– • Clogged fuel strainer (High pressure side) (page 5-106)
• Clogged fuel feed hose
• Faulty fuel pump
– GO TO STEP 11.
– • Repair the open or short circuit in the fuel injector wire
• Faulty fuel injector
– Check the valve clearance and recheck. If compression is out of specification in one or more
cylinders, perform a leak down test before removing components.
– GO TO STEP 12.
– Faulty original IAC valve.
– Replace the ECM with a new one and recheck.
TROUBLESHOOTING
4-3