First question is what did it look like last year? Second question is how many approximate gallons of fuel has run through the filter? You are talking about the Racor 500 element filter correct? When you changed the filter did you drain the housing ? If yes did you inspect it for water? If yes, was there water in the filter housing?
Black colored filter element is evidence of a filter that has filtered a lot of crud. The crud is usually from old fuel, water in the fuel tank, or a bad patch of fuel from a fuel dock.
Everyone has a standard they use for fuel filter inspections and filter changes. Some inspect and change once a season, some every 100 hour, 200 hours and some use the gallons used as a gauge.
The original Racor 500 filter element is light tan in color when installed and dry. It turns to a brown color when saturated with fuel. I change my filters usually at the 100 hr mark +50/-20. I have never seen color change to black. The worst I saw was at 130 hrs approximately 400 gallons of fuel used dark brown element no water.
Newer diesel boats normally do not have much sediment in the fuel tank so the filters stay generally clean and filter the fine dirt and water that is pumped into the boat from the fuel dock. I have seen older boats that over the years have sat and the fuel may have degraded, and water was present this makes a dark looking sediment in the bottom of the tank. The filters pick this up and as Jim said do their job removing it from the fuel so as not to do damage to the rest of the fuel system.
My opinion, change your filter run a tank of fuel through it and inspect the filter again. If you see any dark or black particles in the filter have the tank checked for sediment in the bottom. The boat is to new to have this issue. Did the boat sit for a long period of time with untreated fuel? Maybe you picked up a bad batch of fuel. It happens!
You have not had a performance issue so that is the positive. The filter is doing its job. I would be proactive and have the tank inspected for water and crud in the bottom. It is not that hard to do.
This photo shows one of the fuel fittings I changed to a tee fitting. It is a return line so there is no pickup tube attached to the fitting. I have a pipe plug on the top of the fitting. I use an 1/4" tube with a barb fitting attached to the end. I remove the pipe plug and insert the tube and run it to the bottom of the tank center. I use a oil extraction pump and pull a sample from the bottom of the tank. Inspect it and determine if I need to polish the fuel because of sediment.
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I have installed an Auxiliary fuel tank that I can use to polish the fuel that I take on board. I use this tank to add 20 gallon more fuel capacity and to clean the fuel each time I fill up the tank. This really is not a needed in this type of boat but I did need the extra fuel capacity so I took it one step further.
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