TOHATSU BFT 250A, Service Manual

Page: 95 / 639

4-3
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TROUBLESHOOTING
6. Spark Plug Inspection
Remove and inspect spark plugs.
Is the spark plug wet?
YES – • 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
NO – GO TO STEP 7.
7. Vapor separator inspection
Loosen the vapor separator drain screw and check whether fuel flows out.
Does the fuel flow properly?
YES – GO TO STEP 8.
NO – • 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)
8. Fuel Pump Inspection
You should hear the pump hum when the combination switch is turned "ON".
Is the hum heard?
YES – GO TO STEP 9.
NO – Perform fuel pump system inspection (page 5-114)
9. Fuel Flow Inspection
Inspect the fuel flow (page 5-113).
Is the fuel flow within specification?
YES – GO TO STEP 10.
NO – • Clogged fuel strainer (High pressure side) (page 5-106)
• Clogged fuel feed hose
• Faulty fuel pump
10. Fuel injector inspection
Inspect the fuel injector (page 5-116).
Is the fuel injector normal?
YES – GO TO STEP 11.
NO – • Repair the open or short circuit in the fuel injector wire
• Faulty fuel injector
11. Cylinder Compression
Check the cylinder compression (page 14-33).
Is the compression low?
YES – 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.
NO – GO TO STEP 12.
12. IAC valve inspection
Replace the IAC valve with a new one and start the engine.
Engine starts?
YES – Faulty original IAC valve.
NO – Replace the ECM with a new one and recheck.