Fault Phenomenon: Zoomlion ZLJ5440THB fuel system functions normally when cold. After refueling (operating temperature), engine power fluctuates, white smoke comes from the exhaust, and eventually stalls.

Troubleshooting Process:
– Checked fuel-water separator: draining normal.
– Checked tank bottom: no water accumulation.
– Checked fuel filter: filter not saturated.
– Measured fuel injection pressure at operating temperature: found unstable pressure.

Root Cause: Water enters through the fuel tank breather, causing excessive water content in the diesel.

Required Parts: Fuel filter and diesel replacement.