Since day one (three years ago) my 360 has exhibited a noticeable odor of fuel
on takeoff.  I've been unable to find any fuel leaks and have removed the
header tank and taken apart the fuel lines several times.  It seems worse when
the header tank is near full.  When it is half full, I don't notice the smell.
I've never noticed the smell at any time except takeoff.  I suspect the vent.
I have what I believe to be the factory standard vent setup.  The end of the
vent is about two inches forward of the filler cap.  The opposite end of the
vent tube exits the tank at the rear and bends 90 degrees down at which point
a flexible tube connects.  The flexible tube routes like an 'S' laid on its
side, the other end attaching to the vertical tube that is attached to the
tunnel on the passenger side.  The tube exits about 2/3 rds back the nose gear
door and is chamfered to develop positive pressure in the tube.

I now wish I had routed the vent tube to the front of the tank since I suspect
fuel sloshes rearward, enters the tube, and goes overboard, allowing fuel
vapors to come back into the cabin through various openings.  Nobody likes the
smell, especially non-pilot types.  Since this is the standard setup, has
anybody else had this problem, and if so, what did you do to fix it?

Regards,
Ed de Chazal