I'll add to what I mentioned before.  Connect a long hose to the outlet (inlet to the pump) fitting.  Long so that you can keep one end above the level of the fuel so it won't leak out.  Blow air in to the hose while watching the suspect spot.  If there's a hole there you should see small bubbles as soon as air pressure pushes the fuel level below the spot.  Moderate the pressure to avoid emptying the tube and blowing bubbles at the hard line inlet on the bottom of the tank.  Best method would probably be like the cartoon guy in the Service Manuals.

I submit this for your consideration. IT IS NOT A RECOMMENDATION. Harbor freight has a solar light rope. Charge is good for eight hours, it's eight feet long & it APPEARS to be sealed. It might be worth taking a look at to determine if it is safe to use in that explosive atmosphere.

It is possible to negate the explosive atmosphere in the tank with liberal usage of dry ice. I watched a crew burn a hole in an underground gas tank that had been removed. They dumped a lot of dry ice in the top & waited until the CO2 gas was visibly coming out of the top of the tank. One guy fired up the torch & as I was rapidly retreating to a safe distance, he burned a walk-thru hole in it. I was amazed. This too is not a recommendation. Just thought it was on topic.

If you've got those nail head connectors loose on the sending unit you're half done, they were a huuuge pain for me.  Putting them back is even more fun, FYI.  Dropping the tank is not as bad as you think, piece of plywood on a floor jack, let it down a little at a time and remove the hoses as you go.  The big one at the filler hole is the toughest.  Soak the hose connections and the tank strap bolts the day before with white lithium spray grease, it sticks better and won't drip in your face. 

 

You'll have to drop it sooner or later if the pick up is bad. 

Dry ice is a great idea! I would solder it myself with dry ice. Wash it 2 or 3 times, leave it out in the sun one day. Dry ice and a soldering torch the next.

I guess I would drop the tank and cut out the rectangle as shown with

the supply and return line. Repair as necessary.

Then have someone braze the piece back in.

That issue if that is it is now solved.

My Dremel  tool with cutting wheel would take 3 minutes.

Edited May 26, 20159 yr by lumens