1990 Comp Leaking Gas from Vent

[Knox90Comp]

My comp is slowly leaking fuel out of the vent in the rear portside of the cap, and I can't figure out why.

I winterized the boat over the weekend and the ignition accidentally got left in the ON position for about 6 hours (stupid rookie rushed mistake). I purchased the boat with a keyless ignition; you turn a switch on to feed power to the ignition, type in a code, and hit the green button to start it. The engine is killed by hitting a red kill button on the same code module. After I killed the engine, I forgot to turn the switch off. Therefore I believe that the fuel pump was running and building pressure in the system during the time it was left ON. When I removed the fuel cap (starboard side) it did relieve pressure, but fuel has still been leaking out of the vent for the past two days.

Hoping somebody can give me some insight into what is going on so that I can get the boat stored in my garage. Thanks in advance.

[SquamInboards]

Do you have an electric fuel pump for some reason? I would think your 1990 boat would have a carburetor and only a mechanical fuel pump. Which would mean, it's only pumping fuel when the engine is running. The only time I've seen fuel coming out of a vent (in a boat like yours) is when the tank is especially full, and/or the boat is tilted slightly toward the vent. How full is your tank?

[Wylietunes]

Did you top off the tank prior to lay up?

Are the ambient temps in TN unseasonably warm lately?

Fuel expands when warm and a full tank will simply purge out through the vent. This is very common in the spring when it warms up, and boaters have made the mistake of filling the tank in the fall. If the tank is full, I would suggest siphoning out about 10%.

[Knox90Comp]

I did top the tank off and the temperatures are unseasonably warm here. I'll try siphoning a couple of gallons out of the tank this evening and see if that fixes it.

It didn't even dawn on me that the pump would be mechanical, but it definitely makes sense now.

[NoWake]

Could just lower the tongue of the trailer unless the garage is just to hot, then you'll have to siphon. It is easy to forget how much just 2 inches taking it off the hitch can change these tiny tanks.