step one- remove the top cap then place a container underneath and open the drain tap the fuel flows better with the top cap removed. Use the filter tool to undo the collar.
Unscrew and remove the fuel bowl. Take the collar off the fuel bowl remove the old O-ring then remove the fuel filter make sure if the grommet seal gets left behind that you remove that as well.
Inspect the bottom of your fuel filter housing if this has a buildup of dirt or sludge you'll need to clean this out. Use a piece of rag to clean the sealing surface and the threads. Fit your new filter. Lube up your o-rings. Fit your o-ring to the fuel bowl.
Then apply downward pressure on the fuel bowl while screwing on the collar. Make sure you apply downward pressure and don't let the fuel bowl spin. If you let the fuel bowl spin it risks the o-ring coming off or pinching the o-ring and not sealing properly. On the fuel Pro 382 they recommend tightening it an extra three ribs. Then get some clean fuel and pour it in the top make sure your fuel tap is obviously turned off at the bottom. Fill the bowl right up almost to the top.
Temporarily fit your top cap then go and start the engine. While the engine is running you can loosen off the cap, this will allow the fuel to slowly drain down. Once it gets down just above the collar screw the top back up. The Davco will find its own level, as the filter is in service the fuel level will rise. When the fuel level gets almost to the top this indicates that the filter needs changing