I'm getting a code P0455 which would appear to be a loose fuel cap or something that is preventing a good seal. I've found that the outer lip of the fuel filler neck is chipped / broken. Pics attached:

http://i31.photobucket.com/albums/c385/rcknrbn/IM002101.jpg
http://i31.photobucket.com/albums/c385/rcknrbn/IM002098.jpg
http://i31.photobucket.com/albums/c385/rcknrbn/IM002097.jpg

It would make sense that this chip is preventing a good seal. However, it looks difficult to remove the plastic filler neck. The metal neck actually has the broken plastic piece which is a sleeve (?). Anyone ever replaced this piece. Difficulty?

 

I have a similar problem to yours but mine is only cracked.
I have super glued it twice so far, and each time it fixed the code.
My next fix attempt will be with epoxy, and some light filing to get a good seal surface.
I have not tackled a replacement yet, but was leaning to a junk yard replacement filler tube as a last resort.
Looks like the plastic is glued into the tube, so short of cutting it out, don.t think it is a replaceable item by itself.

Would like to hear if anyone else has a fix.

 

those 3 bolts u see around the filler cap? remove them and you can pull it right out of the slot from under the bed. There should then be a hose clamp on the metal neck that goes to the tank. remove it and slide the entire thing off.....

 

I lowered my tank to replace mine. Its easier to get to the rubber lines on the tank if you do. There are 2 lines going into the tank a metal one & a rubber overflow line.

 

It's easier to remove the box then it is to drop the tank on the ground. If you have a hoist and tank jack it's slightly easier. But I still like takin the box off and moving it back 2 ft. to open up the top of the tank.

 

I agree. Here you see where you would be working on the hose connections. Not Reeeeeeal good!