I am working on my 76 280z.  The recess behind the gas door was rusted out in one corner.  See pictures below.  I noticed that the backside was seam sealed all the way around.  

Where is gasoline or more importantly water supposed to go when it gets in there?  Obviously you don't want to have gasoline leak on the back side of the quarter panel because the smell would be inside the cabin.  Has anyone welded in a nipple in the corner and attached a hose that runs down and empties on the ground?  That's my current plan.

 

 

My quarter panel was rusted around the bottom edge of the filler area, but I didn't have any damage on the recessed area.  It looks like to me that the 'natural' drainage would merely flow out and down the outside of the quarter panel.  I wouldn't think your nipple would be at any lower point than the outer edge of that recess.

The only Zs that tend to be rotten in the filler neck area are either badly rusted or salt road cars. I would assume when finished repairing the car, salt exposure will be limited or non existent. So I think the drain is unneeded. Also if you made a drain it is likely to rot from salt too. So it probably won't stop the issue

3 hours ago, fusion said:

I am working on my 76 280z.  The recess behind the gas door was rusted out in one corner.  See pictures below.  I noticed that the backside was seam sealed all the way around.  

Where is gasoline or more importantly water supposed to go when it gets in there?  Obviously you don't want to have gasoline leak on the back side of the quarter panel because the smell would be inside the cabin.  Has anyone welded in a nipple in the corner and attached a hose that runs down and empties on the ground?  That's my current plan.

 

 

I see you are in Minnesota. They salt the roads in Minnesota, don't they?

That lower front corner of the filler pocket can collect dirt, and when it gets wet, it tends to stay wet. 

Patch in some new metal, or see if you can find a good used part from a parts car. You might use some of the seam sealed  to fill that area, after assembly and primer, to direct moisture from collecting there.

Then wait for the spring rains to wash the roads off before the first drive of the season every year.

 

Thanks for the comments.  I suspect that it is supposed to drain out the front.  It's hard to judge since I cut the panel out for repair.  I am in Minnesota but the car spent it's whole life in Texas so not sure how it rusted in there.

If it was down near Houston or Corpus Cristi, it rusted from the salt water breezes. Not all of Texas produces low rust cars