[updated:LAST EDITED ON 14-Dec-02 AT 04:35 PM (EST)]Well, there isn't any "pressure" in the tank save for the fuel that is in there pushing down on the bottom of the tank due to its weight.

I know you don't want to do this, and you don't want to hear this, but I also have a 1993, and I had a similar problem.
Deduction: 1993 (and possibly others') rear metal gas tanks were, and are, crap!

(and they are a time-based deteriorating component, not mileage based... ours went at similar times even though I had 84,500 miles on mine when I changed it out)

My pinhole was near the top - are you planning on covering the whole tank while you're under there?

Do yourself a favor. Do yourself a BIG favor. Change the tank out for a new one. I'm going to predict that you are probably facing seeing many more pinholes within the next year or so.

While doing your changeout, replace the fuel pump, the fuel pump's screen, and the outer, if not the outer and inner, fuel-filler hoses.

Sorry, but I just had to get that out. I don't feel I would be helping you by writing for your plan, or by ignoring what seems obvious (based my the additional knowledge I have of another 1993 pinhole - that isn't to say it should have been obvious to you).

I wish you the best in your endeavor. If you don't address it now, just plan on finding a place, getting the tools, and buying the parts, to do it fully sometime soon.

Best,