Gas tank Leaking

I have a 17 foot express bass boat, with a 10 gallon Portable plastic gas tank with the plastic screw on cap, if it’s more than half full, gas leaks around the threads , Not out of the vent on the cap, I know it’s common for those portable tanks to leak a little gas around the cap , But is this anything I need to worry about and replace the tank, not sure I can find another cap for this tank,
The gasket looks good inside the cap ,so I’m not sure why it’s leaking ,

Do you loosen the cap to let the air out of the tank before you do any fishing? Also could be a lot of expansion from the heat also. Could get another 10 gallon tank and try that out and see if you get the same results?

Your tank must be vented. Or it does what it’s doing.

Yes I have the vent screw loosened and is getting air and it’s not choking down.

Ok I’d be looking for another tank. That one sounds compromised.

replace the tank fuel tanks are cheap compared to fuel getting into the bilge an a spark from a battery or other electrical connections could lead to a disaster

I hope this question is relevant to this thread. If the fuel tank is vented, why does it release pressure when I open the fuel tank cap to fill up?

Many EPA rules and regulations went into effect in 2009. Vents cannot be open-air vented like they always have been in the past. Portable tanks have even more restrictions. Some of the 2014 and up fuel tanks are pressurized and have a relief valve that will open if the pressure gets too high.