This last summer I noticed a not small amount of diesel in my bilge. I've looked under the engine and found nothing. Also put some paper towel on under the fuel tank, left it for several hours, and detected nothing on it when I pulled it out. The only thing I can think of is that at the end of the previous season I had a dockhand fill the tank and she put in way more than I expected, considering how little I'd used the engine that season.
Is it possible that the tank was overfilled and fuel leaked into the boat via the vent?
I would check your fuel lines, fuel pump and primary fuel filter for leaks. When the power is turned on at the ignition switch, the fuel pump is activated and the lines are pressurized. You can check if fuel is dripping anywhere along the fuel lines from tank to engine that way.
Ed Ray
s/v Rocinante
1986 C36 Mk I #610 std / fin
Santa Monica, CA, USA
"Sejl mens brisen blæser" - Danish proverb
My primary filter (Racor15p) was leaking. I bought a rebuild kit and replaced all the O rings and such and no more leaks.
"Nauti Seahorse"
2001 C36 MK ii. #2011