Suzuki DF2.5 Service Manual page 201

DF2.5 (Serial No. 410001 and later) 19
6. Loosen the screw 6.
Remove the fuel cock 4 from the fuel tank 5.
7. Drain all fuel from the tank.
INSPECTION
Fuel cock
Check the filter.
If clogged or damaged is found, clean the filter or replace the
fuel cock assy.
Inspect the fuel cock. If leakage, deterioration or other damage
is found, replace the fuel cock assembly.
Fuel tank
Inspect the fuel tank. If crack, leakage or deterioration is found,
replace the tank.
If water or other contamination is found, drain and clean the
tank.
Tank cap
Check that the fuel tank vent opens and relieves internal tank
pressure properly.
If vent is suspect, replace the tank cap.