Husqvarna HUV 4421 4421-D/DX/DXL User Manual page 51

Biodiesel is an excellent medium for microbial growth and contamination. Microbial contamination can cause corrosion
of the fuel system and prematurely plugged fuel filters. See following NOTE.
NOTE: Use of biodiesel may result in premature failure of fuel system components. Kubota has documented problems
such as plugged fuel filters and deteriorated fuel lines during testing of biodiesel.
Biodiesel can damage painted surfaces. Be sure to remove all spilled fuel immediately to help prevent damage to
painted surfaces.
If biodiesel will be used in the Kubota D722 engine, be sure that it meets the following requirements:
• The fuel blend should contain no more than 5% biodiesel by volume.
• The petroleum portion of the fuel blend must meet ASTM standard D975 and the biodiesel portion of the fuel
blend must meet ASTM standard D6751.
• For Europe, the fuel blend must meet the EN590 standard. See following CAUTION.
CAUTION
• Never use any fuel that does not meet specifications or fuel in which the contents cannot be identified.
Using blends higher than 5% biodiesel content can affect engine life and cause deterioration of hoses,
tube lines, injectors, injector pump and seals.
• For more information on these fuel standards, please contact your nearest Kubota dealer.
If biodiesel is used, be sure to apply the following guidelines:
• Ensure the fuel tank is as full as possible at all times to prevent moisture from collecting.
• Ensure that the fuel tank cap is securely tightened to prevent water from entering the fuel tank.
• Drain all water from the fuel filter daily before operating vehicle. See Draining Water from Fuel Filter.
• Check the engine oil level daily before the engine is started. See Engine Oil Level Check on page 39.
• Before vehicle storage, run the engine with conventional diesel fuel for at least 30 minutes to flush the biodiesel
from the engine. See Preparing the Vehicle for Extended Storage on page 31. See following NOTE.
NOTE: Biodiesel does not have long-term stability and must not be left in engines longer than three months. This fuel
type attracts moisture and may contain higher water content than conventional diesel fuel.
Fuel system maintenance, cleaning, and fuel line replacement are required more frequently for engines that are
operated with biodiesel.
DRAINING WATER FROM FUEL FILTER
Diesel Vehicles Only
Water should be drained from the fuel filter daily. The fuel filter is mounted on a plate by the lower seat support
panel (Figure 36).
1. Position a pan under the fuel filter.
2. Lift the passenger-side seat.
3. Locate the valve (1) on the underside of the filter. Turn the valve clockwise until water begins to stream from
the filter.
4. Drain the water until it changes color (to fuel). See following WARNING.
Fueling Instructions
HUV 4421 Owner's Manual Page 49