on my car there are two 1/4" lines on the driver side of the tank. the one on the left has the vent with a 180 degree turn down. the one on the right goes up thru the trunk. the sending unit has a 3/8" fuel line and a 1/4" return line. i have had fuel slosh out the 180 degree vent with a full tank. the gurgeling is probably the fuel return line relieving pressure after the engine is turned off. hope this helps.