Please replace fuel filter in the oil groove every 100 hours or every 6 months.
1. Turn off the fuel cock and remove sedimentation cup and O-ring gasket. 
2. Clean sedimentation cup and O-ring gasket with non-inflammable solvent. 
3. Put back sedimentation cup and O-ring gasket.
4. Turn on fuel tap to check whether there is oil leakage.  If there is oil leakage, replace O-ring gasket. 
5. Clean fuel filter and filter screen to remove filth on the filter screen and check whether the filter screen is broken. If the filter screen is broken, it shall be replaced in time.