Fault Phenomenon: Toyota 8FD25 diesel forklift starts normally when cold. After stopping for 10 minutes (operating temperature), starting is difficult, requires prolonged cranking, and eventually fails to start.

Troubleshooting Process:
– Checked battery voltage: voltage sufficient, terminals tight.
– Checked starter motor: carbon brushes worn normally, rotor no rubbing.
– Checked glow plugs: heating normal when cold.
– Measured starter motor current at operating temperature: found current normal but RPM slow.

Root Cause: The engine cylinder block deforms due to heat, causing excessive starting resistance, or injector nozzle dripping causes vapor lock.

Required Parts: Injector nozzle assembly or engine overhaul kit.