Re: Fuel Leak ?
Billflo:
I've got a Lund 1700 Fisherman, similar to yours. Mine has a 26 gal gas tank similar situated under the floor board.
First, under no circumstances should filling the gas tank discharge any gas into the boat bilge area or anywhere else inside the boat. If you note on your tank, like mine, there is a two line connection to the tank. One line is a fill line, the other is a vent line, both connect to the fill fitting on the outside of the boat. Even if you discharge fuel when filling due to the gas pump not tripping off, it should not enter the boat, but simply squirt out the overflow vent next to the fill cap. I nearly always spill gas out the fill vent when filling my gas tank and never have had gas in the bilge.
Regarding your apparent leakage with the fuel float sending unit - that's the device shown in your picture - if it's leaking, that means you either need to tighten the mounting screws or pull the device off the tank and reinstall the gasket. This sending unit can only be mounted in one direction (or rotation) since the mounting holes are not symmetrical. The holes will only align in properly in one location. It's no big deal to pull this sending unit. Just remove the screws and the unit will lift right out. Of course, be very careful to not drop anything into the tank. I would not recommend using any gasket cement on this device since you may want to remove it in the future. One unit I had used a rubber gasket, the other a cork gasket. Both created a gas tight seal without any gasket cement. I just went back and looked at your last photo. No question about it, the gasket is damage. You will need to replace that gasket. Get one from WEMA, see link below.
For reference take a look at my posts a couple of months ago about this WEMA sending unit and the difficulties I had with mine. If you have questions about the gasket or the sending unit, call WEMA directly,
http://www.wemausa.com/contactus.htm
Also, if you need to drain your tank here's an easy way to do it - assuming you have an outboard engine. Simply disconnect the fuel line from the engine. Then disconnect the fitting from the hose that connects to the tank. Extend and drop the hose over the transom and use the fuel priming bulb to start a siphon from your boat's fuel tank into containers on the ground. It's a bit of a slow process due to the gas tank height and line losses, but its a simple way to get the gas out of the tank.
Hope this helps.
Bob
I have a 2000 Lund Fisherman Adventure. 2000 Merc Optimax 135, after returning from the lake yesterday I filled the tank ( topped it off for winter storage) This am the garage smells like someone dumped a gallon of gas on the floor... I have only had this boat for about a month & around here, you just cant go thru alot of gas ( lots of no wake lakes)..... to help me find the problem, is this boat model known for an specific suspects in the fuel system.. 
