Thanks all for the replies.
Short version of the last several months of events related to my fuel system/engine.
18 gallon tank, original to the boat as far as I know (~20 years). Purchased the boat in April had not gotten to change fuel filter at the dock first time so you don't have to do it "out there."
But hey, why change the filter today, I could be sailing.
Ran fine all summer (~30 hours), basically no water in separator. In November filled up with diesel at my marina, took the boat out toward the bay. In the middle of a very narrow channel, engine lost power and died. Couldn't restart. Got the sails up, headed back toward marina with Admiral at the helm. I went below to change fuel filter. Wasn't going to happen, prior owner and the phrase hand tighten weren't on the same page (should have known that from the oil filter change after I bought the boat). Got the boat back to the marina entrance and had 20 knts on the nose. After several attempts, realized I have unlimited towing insurance. Dropped the anchor, popped a cold adult beverage and waited to be rescued.
Back at the marina, lots of water in the small separator (where did that come from)
. Ended up having to drive a screwdriver through the filter to get it off. That is a little nerve-racking, yeah I know diesel not gas, but I still don't like the idea. Replaced the filters and started operating the lift handle to bleed the system. After 2 beers (I mean 30 mins) without any sign of bleeding going on, went to the chandlery for advice. Bought a small primer bulb that I placed inline between tank and primary filter. Two squeezes on bulb and entire system was primed. Ran engine at dock at varying RPM's for about an hour, congratulated myself on a job well done and called it a day.
Next sail, checked the separator (emptied a small amt of water, probably more than all summer) motored out of the channel to the bay (30 mins), had a great night sail, coming back in started engine. The engine started fine, ran for 10 mins and then lost power and died, was able to restart briefly but not keep it running. Checked the water seperator, lots of water and crud. Squeezed the bulb, was pushing fuel all the way through the system, so not a completely blocked fuel filter. Night-time, unlimited towing, narrow channel, easy call. Tow Boat US to the rescue again.
Now thinking I got a bad batch of fuel from the marina with just enough water to bloom 20 years of "algae" wishing I had an algae-x magnet
. This combination of crud and water was quickly overwhelming the limited space in the separator on a 120 series and making it down line. Went and bought Star Tron Enzyme treatment. Changed the fuel filters again ($20 + $8) and primed system. Ran engine at dock for 1 hour, congratulated myself and called it a day.
Next sail, 30 mins to the bay, ran fine. Great sail while you AFOC's where in Chicago, restarted for the channel, had loss of power but was able to get restarted and ran fine the rest of the way in.
I think (knock on wood) that the problem was/is moisture in the tank (found out yesterday the marina had a diesel tank leak the week before I filled up), blooming bacteria in my 20 year old tanks.
The Star Tron seems to be helping, but I expect to need to change several more filters in the next few months to catch all the crud.
The 500 is the smallest capacity filter that doesn't use spin-ons that I can find (I agree it is overkill), but I like the increased water seperator space (mine holds about two tsp) for the next time this happens.The much cheaper replacement elements $10 vs $20. I feel it is easier (for that matter possible) to visually check the status of the filter. Although I will probably buy a vacuum gauge for it.
The good news is now I am slightly more comptent at one more component of owning a sailboat, only 3684 more topics to go.
Okay, let me have it. I'm open to all ideas/opinions.