After a couple hours cruising around Elliott Bay, the port engine died as I entered the marina. I was able to dock with one engine and the bow thruster, thankfully. About 30 minutes later it started with no problem. Dirty fuel, clogged filter, air in the line??? The racors have 100 hours but the diesel is a couple years old.
Before you get talked into a wild goose chase, you need to supply quite bit more information.
Did you perform any maintenance or change anything before going for the cruise?
Did the engine quit suddenly without any warning sign like slow loss of power or slowly diminishing rpm? Did it "stumble" for a while before quitting?
Did the engine sound normal before it quit?
Was it hot?
Is there oil in it? Enough? Normal color and smell?
Was there any smoke or unusual smell?
Any unusual noises?
Were the gauge readings normal until the engine quit?
Were they normal after you restarted it?
Are both engines fed from the same fuel source?
What happened after it quit? Did you attempt to restart immediately? Did it crank normally? Did it "want" to start but did not?
Would it idle normally but quit again when you put it in gear?
While the incident is still fresh in your mind, make some notes of everything you can recall about before during and after.
Don't just do something ... stand there and think about it for a while.