Close the fuel inlet valve and drain the filter through the bottom tap.
Remove the plastic bowl by taking out the four metric bolts holding the clamp ring. Make this easy for yourself by getting a socket on an extension bar with a 1/4 ratchet drive, it is a real pain with a spanner. Clean bowl and inner gubbins with rag. Replace with a new bowl seal.
While you are at it you will want to put a new filter in the top. Undo the four bolts and remove top casting. Remember what you see inside or take a photo of it. Remove the plastic filter pressure plate and filter and replace filter with new. Refix with new seal.
All the seals etc come in an expensive kit. I have never succeeded in buying individual parts.
Unless the filter is very badly soiled you can wash them in paraffin, inspect them for damage cuts or nicks and, if serviceable, dry them out for further use. This sounds very old school, but the filters are expensive and are designed for extended use and in situ cleaning by backflushing (details available on the webbette).
And when I put the bowl back in its place and open the fuel inlet valve will it fill up when I start the engine without getting air in the high pressure pump or do I need to pump by hand and somehow bleed the engine.
I do not put anything in the fuel but may be I should. I have tried to drain from the botom of the reservoir but I cannot take it all. This fill of dirt is from starting the engine for a short time while sailing in strong winds and in moderate waves.
Turn your main supply back on and open the bleed screw on the top of the filter (this is normally a tall hexagon, it may have a slot in it). This will allow fuel to flow and begin the fill the bowl, as air escapes from the bleed hole.
When the bowl and filter are nearly full, the bleed hole will start to splutter and then emit pure fuel; at this point nip up the screw. There is always a bit of mess, a panty liner is a good tool for cleaning up.
Your engine may then run, or not. I would give it a go. If it won't run then engine bleeding may well be needed.
As Easticks has said the filter looks a bit manky, you might show the contents to someone who knows the tell take signs of fuel bug. I should treat the fuel anyways, I bought some pretty inexpensive stuff last year that claims to both treat and protect.
