And of course no one has mentioned the fact that the fuel selector is also in the cabin and can be be prone to leaks in the same way as the primer, with the fuel gathering under the floor. By the way do you turn the fuel selector to OFF in the 152? If I remember correctly there was an instruction to do this because if it was not used often the fuel selector would stick and eventually be difficult to move. This could prove a problem if an engine fire was detected.