FORD 1999 F-550 v.1 - Manual (Page 206)

Fuel Filter
Your vehicle is equipped with a fuel filter that is mounted on the
underbody.
For fuel filter replacement, see your dealer or a qualified service
technician. Refer to the Scheduled Maintenance Guide for the
appropriate intervals for changing the fuel filter.
If you replace the fuel filter, replace it with an authorized
Motorcraft part. The customer warranty may be void for any
damage to the fuel system if an authorized Motorcraft fuel filter
is not used.
ESSENTIALS OF GOOD FUEL ECONOMY
Measuring techniques
Your best source of information about actual fuel economy is you, the
driver. You must gather information as accurately and consistently as
possible. Fuel expense, frequency of fillups or fuel gauge readings are
NOT accurate as a measure of fuel economy. We do not recommend
taking fuel economy measurements during the first 1 600 km (1 000
miles) of driving (engine break-in period). You will get a more accurate
measurement after 3 000 km–5 000 km (2 000 miles-3 000 miles).
The advertised fuel capacity of the fuel tank on your vehicle is equal to
the rated refill capacity of the fuel tank as listed in the Refill Capacities
chart in this “Owner Guide.” The advertised capacity is the amount of
the Indicated Capacity and the Empty Reserve combined. Indicated
Capacity is the difference in the amount of fuel in a full tank and a tank
when the fuel gauge indicates empty. Empty Reserve is the small amount
of usable fuel remaining in the fuel tank after the fuel gauge indicates
empty.
The amount of Empty Reserve varies and should not be relied
upon to increase driving range. When refueling your vehicle after
the fuel gauge indicates empty, you might not be able to refuel
the full amount of the advertised capacity of the fuel tank due to
the empty reserve still present in the tank.
Maintenance and care
206