fuel pump replacement on 1997 GMC 1500 Pickup

how is the "cam ring retainer" removed to acces the fuel pump for replacemetnt.
is it just twist and turn or is there a tool that is needed.

Asked by for the 1997 GMC 1500 Pickup
I'm sure GM have a special tool but I have always used a screw driver and tap the ring counter clockwise to remove it. On reassemble ensure the sealing gasket/O Ring is properly installed or it will result in a Evaporative Emission failure.