Fuel tank opening

A method of blow molding a fuel tank, comprising:

• positioning a warm parison within an open mold;
• closing the mold about the parison;
• piercing the parison with a first piercing head of a first needle into communication with an interior of the parison;
• injecting a pressurized gas through the first needle into the parison to displace the parison against the mold to at least partially define the fuel tank;
• after injecting pressurized gas through the first needle into the parison, piercing the parison with a second separate piercing head of a second separate needle larger than the first head of the first needle and circumscribing the first head of the first needle by moving the second needle relative to the first needle to at least partially form an opening in the fuel tank larger than the portion of the first needle which pierced the parison;
• and
• removing the fuel tank from the mold with the larger opening at least partially formed therein.