2002 honda ace gas tank pressure

If the tank was completely filled with cool gas, and the bike was parked in the sunshine, the gas in the tank warming up may have expanded, pressurizing the gas tank. Gas caps are supposed to be vented to allow air to enter as the fuel is used, but they don't stop the tank from having pressure inside. Try removing the gas cap to see if the leaking stops.
I suggest that you call the dealer that you bought it from and confirm the problem..

Under the seat will be a retaining bolt that holds the tank in place. Switch off fuel at the petcock. Remove fuel line. You may also need to discount the fuel gauge wiring under the tank. Once you have removed the retaining bolt slide the tank back as it will be sitting on two front rubber mounts

Sounds like gas tank is not venting properly. A vacuum is created and the fuel pump can't **** more fuel for the motor. When it dies, loosen the fuel filler cap to hear if there is an in-rush of air and if it restarts immediately. If this is the problem you could drive short distances with the cap on loose, but could be a hazard in a rollover. Fuel would spill out.

There should be some bolts behind the seat or under the seat than there is on at the back of the gas tank

check for water in gas

first take off gas tank so you can access radiator cap......just lossen it..then find drain plug and let her rip..i by the way race my bike on and off and use Kool-Aide as a substitute because of racing requirement and have had no trouble with it.runs a little cooler actually.get all those fairings out of the way and it should be very simple.

It sounds like the vent in the gas cap is not venting (pluged up).Fuel is like coca cola, when it gets a little shake up it expands.See if you can check the vent in the cap.

I am not going to lie, I came across this in another forum a while back and I would love to retype it and interpret it here but it is too much. I looked at it and verified that the information here is information that could be found through my scan tools so here it is!

P0440
The fuel tank pressure is atmospheric pressure after the vehicle is driven for 20 min (2 trip detection logic).

Possible Problems
Fuel tank cap incorrectly installed <= Most common
Fuel tank cap cracked or damaged (Toyota part only)
Bad vapor pressure sensor/circuit
Vacuum hose cracked, holed, blocked, damaged or disconnected 
Hose or tube cracked, holed, damaged, or loose
Fuel tank/filler neck cracked, holed, or damaged
Charcoal canister cracked, holed, or damaged (collision)

In above description, check hoses between vapor pressur sensor and VSV for vapor pressure sensor and charcoal canister. Also, hose between charcoal canister and fuel tank.