Fuel pump questions

[bruce plecan]

fuel pump question:
on some chevies, they run a pressure releif valve, so the tank doesn't
build up that much pressure that it takes several minutes to blow down.
Usually it happens in the time it takes to unthread the gas cap.  Usually
easy to spot, there by the gas tank with usually a 3/8" hose going to it
and then a plastic devise about 1 1/8" diam. 2" long.  With the hose
going no where else.  It's also easy to miss the vent some gas caps have
in the clicking (racheting head) devise.
  HTH  Bruce   nacelp at bright.net