The best way I have found to change the fuel lines at the tank, and it works great you will only drip out what is in the fuel lines, nothing will come out of the tank if you do it right. We put fuel lines on a lot in the shop I work at so I have done this many times, and it works with a nearly full tank.

If you have a shop vac. Pull the cap off the filler neck. Then stick the shop vac hose into the filler neck a little ways. Not to far you don't want to suck up and fuel. You just want to create a little vacuum in the tank. Turn the shop vac on and make sure you aren't sucking up fuel. Then crawl under the car. And take a catch pan with you. Pull the hose clamps off one of the fuel lines you are removing. And break the hose loose on the barb so it will come off easily and slowly, not all at once with a big jerk. Then take one end of the hose off and be ready with the catch pan. If you have the shop vac setup good, no fuel will come out of the tank, but the fuel in the line up to the front of the car will drain. The slight vacuum in the tank pulls air through the hole in the tank instead of it draining all over you and the floor.

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