Since you did not give us any info on the motor, I assume it is a diesel.
REPLACING THE FILTER
Removal: Disconnect battery ground cables from both batteries.
NOTE: When the battery has been disconnected and reconnected on vehicles equipped with Electronic Engine Controls (EEC), some abnormal drive symptoms may occur while the EEC processor relearns its adaptive strategy. The vehicle may need to be driven 10 miles or more to relearn the strategy.
Place a container under vehicle and drain fuel from fuel filter.
Remove water drain tube from bottom of filter assembly.
Unscrew water separator drain bowl and remove.
Unscrew fuel filter element and discard.
Installation: Clean gasket surfaces of the fuel filter adapter to prevent contamination.
Lightly coat filter sealing gaskets with clean diesel fuel.
NOTE: To avoid fuel contamination do not add fuel directly to new filter. Allow engine to draw fuel through filter.
Screw new filter element onto filter base until seal contacts flange.
Tighten filter another 180 to 300 degree turn.
Screw on water separator drain bowl. Tighten another 180 to 300 degree turn.
Install water drain tube.
Clean up any spilled fuel from top of engine.
Connect battery ground cables to both batteries.
Run engine and check for fuel leaks.
DRAINING THE SEPARATOR
Fuel Filter/Fuel Heater/Water Separator
A WATER IN FUEL indicator lamp is provided on the instrument panel to alert the operator. The lamp should glow when the ignition switch is in the ON position to indicate proper lamp and water sensor function. If the lamp glows continuously while the engine is running, the water must be drained from the fuel filter/fuel heater/water separator manual drain valve as soon as possible to prevent damage to the fuel injection system.
Drain water from the fuel filter/fuel heater/water separator manual drain valve whenever the warning lamp comes on or every 5,000 miles. The WATER IN FUEL lamp will glow when approximately 3.5 fluid ounces of water accumulates in the separator.
Stop vehicle and shut off engine.
NOTE : To avoid engine stall-out caused by air entering the fuel system, do not drain fuel/water separator while engine is running.
Place an appropriate container under the fuel filter/fuel heater/water separator drain tube to collect drain fluid. The drain tube is attached to the manual drain valve at base of water separator drain bowl.
Manually open drain valve by unscrewing. Allow drain valve to remain open approximately 15 seconds or until clear (water-free) diesel fuel flows from drain tube. Close drain valve by threading into water separator drain bowl until liquid no longer drains from drain tube.
WARNING : Ensure that drain valve is fully and securely closed.
Re-start the engine and check WATER IN FUEL lamp. The lamp should not glow. If it continues to glow, have fuel system checked and repaired.
Drain all traces of water from the fuel filter/fuel heater/water separator as outlined at (5,000 mile) intervals as specified in the maintenance schedule. Refer to MAINTENANCE SCHEDULE. At this service interval, if the warning lamp is not glowing, examine the draining fluid to determine when clear diesel fuel flows from the drain tube. Stop draining procedure as soon as clear diesel fuel appears.