quick question. How can you remove the bung nut without proper tool and little damage? There is no real working room in wagon. Any reply greatly appreciated.

I think the tool that Haroon refers to is called a sink basket wrench also known as a spud nut wrench with two parallel finger-like jaws that adjust sideways. If you don't have access to one you can just as easily tap the bung loose, much like tapping the lid off a food jar except you're working around the inside edge. Use a drift (maybe 1/2" by 6" to 12" long) at a shallow angle into one of the bung notches. Strike the drift with a hammer a few times (counter-clockwise direction of course). Work your way back and forth on all the accessible notches. The bung will soon start to loosen. Penetrating oil could be applied first, but I've never needed it. You should be working in a well ventillated area and ideally you will use a brass drift (to avoid sparks), but an piece of bar stock or even a large slot screwdriver will do. There is plenty of room to work through the access plate hatch. Wagons have full headroom over the hatch and are a piece of cake. Sedans are only slightly more awkward. Just avoid slipping and skinning your knuckles or damaging a hose nipple. The hammer and drift method can also be used to re-tighten the bung.
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-Dave (not to be confused with a real expert, just goofing around at this)

As suggested here, I used a plumbers pipe wrench. Its adjustable and works just like the tool.

thanks

It's funny someone asks. I just replaced the small hose for the in tank pump and I used a 3/8" long extension, some WD-40 and a ball peen hammer. Blow off the dirt and crud, spray liberally with WD-40 tap with the hammer and 3/8" extension to loosen and work in the WD-40, get a cup of coffee then tap the bung nut off. You have to tap it at several different locations at opposite sides of the bung nut and it will come off. THe worst part of the whole job was the fuel return line. I couldn't get the flare nuts loose under the car and ended up cutting the hard plastic hose off and replacing it with fuel line and double clamps.