Ok since about 1980 the fuel pumps are now located in the gas tank. The the only way to replace one, is to drop the gas tank. Disconnect all the hoses and fuel lines that you see leading to the fuel tank. jack the vehicle up and support it on jack stands. Should be two straps that support the tank. Loosen the two nuts. May have to drop the exhaust, not familure with your type of Vehicle's locatin of exhaust design. Ok here the deal. if you have close to a full tank i would recommend having a hydrallic jack with a peice of wood on the lift so it won't puncture the gas tank, or just let it fall. Some come out in a 45 degree angle. Once the tank is out, disconnect electrical clips. You will need a screw driver and a hammer. There is a circle metal sleave. Take the screwdriver and put it on the little lip and hammer it off. It's like a screw. Pull the pump out. make sure to get a new pick up screen and fuel filter. It's kind of like changing your oil and not the filter. Now it may sound simple. Usually it's harder to put the tank back in then it is comming out. You may want to take it to a mechanic shop. We just did one on a 88 Cadillac and charged him $250.... But believe me it will save you the agrevation. Not saying it will be hard. but everyone I have done. has been a pain. Hope that helps out some. to get a better understanding of what is involved.
If it's been sitting overnight likely there isn't much pressure left in the fuel system.
1)Take the gas cap off and wait for the hissing to end. Put the cap back on.
2)The fuel pump assembly is located right behind the rear seats in the trunk. Remove the carpet, take out the cardboard over the spare tire. It has a flexible part covering the fuel pump. Flip this over and put the cardboard back in. Now you will be able to lay in the trunk with access to the pump without impaling yourself on the thing that keeps the spare tire in place. Sounds kinda confusing here but its simple when you can actually see it.
3)Remove the 4 12mm bolts holding down the cover over the pump.
4)Disconnect the two electrical connectors. The one on the drivers side is for the fuel tank float, the other one is the pump.
5)Take off the 17mm banjo bolt. Don't lose the washers (one above the fuel line, one below). Move the fuel line out of the way.
6)The fuel return line has a clamp on it. Take a pair of pliers, squeeze it, and then move it along the line several inches so it is out of the way.
7)Pull off the fuel return line.
8)Remove the six or so 12mm nuts holding the pump assembly down.
9)Take the pump assembly out-- it has a sock on the end so it will take some wiggling at an angle to get it out of the hole.
10)Press on the rubber on the bottom until it comes out of the assembly. Take the sock off (there is a ring holding it on). Pull out the electrical connectors. Pull the fuel line hose off.
11)Take the new pump and just do the reverse of these instructions.