Originally Posted by steve-ribnet
Eek! Not had that problem before. The design of the mercury QR fuel plugs - and the yam ones from memory- is that they positively clip in place with an indent in the barb that the metal lever mates with to prevent it working loose. The retaining spring force is pretty high - couldn't see how it would work loose or jump out unless the connector lock ring was plastic and worn, or lever was worn... I chose a solid brass connector on the filter for this reason
I recall using a cheap aftermarket connector on a portable fuel tank that suffered poor mating (I'm sure we all suffer from poor mating at one time or other ;-) )...it leaked if you wiggled it. not wishing to question the quality of your connectors of course Trevor!
I thought the same as you - that the metal spring clip should prevent it working loose. I used the same brass fittings that you have on your filter (are you sure that's your photo and not one of my old setup?)
Anyway - Back to A1an's original question...
What I ended up doing was to have a brass fuel pipe T before the filter - with two hoses going to the fuel tanks and in-line fuel taps in each hose so we could select which tank to use (or have both turned on).
With 4 fuel bladders around the boat and two plastic tanks under the seat it meant we could always have two tanks connected at a time and still swap them on the go.