Regal 3300 Owner's Manual page 117

Systems
Fuel Fill/Vent
The fuel fill fitting is labeled "gas" and in addition displays the
international symbol. When fueling the boat keep the fill nozzle in
contact with the fuel fill pipe since it decreases static electricity. Always
use the recommended fuel octane rating as specified in your engine
owner's manual.
Extinguish all flame-producing agents before fueling!
Currently, domestic EPA-compliant fuel tanks vent fumes back into the
fuel tank system. While the tank is filled, air displaced by the incoming
fuel is vented through the fuel system charcoal canister.
Your vessel uses a combo type (internal vented) fuel fill. Both the fuel
fill and vent occupy the same cavity under a protective cover. If fuel
overflows through the vent, the design forces it back into the fuel fill
hose and tank.
A seasoned skipper will hear a distinct sound as the tank nears the "top
out" or full mode and may see fuel overflowing back into the fuel hose
through the vent. DO NOT OVERFILL THE TANK. This helps
avoid any overboard spills that harm the environment. There is a key
that fits the fuel fill. Use it to secure the fitting from leaking fuel. Store
the key in a safe place so it can be easily found for fueling. Check the
vent fill screen periodically for debris.
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