Bring your ears close to the seat/tank and listen, if you can hear the fuelpump running for a few seconds after (ignition) key on.
Is the fuel tank cap uncovered so that it can breathe? When you remove the fuel tank cap on the emty or half empty tank, is there a vacuum that can be heard also while removing the cap?
xciting 250 carb or xciting 250i injection?
mechanical fuelpump versus electrical fuelpump?
mechanical fuelpump is cheaper, electrical fuelpump is more expensive.