www.RX7fb.com

well it seems not to leak.....I had no idea how much fuel was in it, lowered out on a jack, plugged pipes and rolled it around, no leaks, it was heavy, very, and I got 46 litres syphoned out of it!

That's great news.

If you can, I'd try and take a peek inside with one of those cheapo miniature USB cameras to see if there is any rust inside, particularly on the top of the tank. I did that with mine and was amazed to see only a few spots of surface rust. From what I've heard the tanks tend to rust from the inside out, especially where condensation can gather on the inside top of the tank.

This sort of camera (Windows & Android version: £5.39): https://www.ebay.co.uk/itm/USB-Endoscop ... %3A2334524

The tank being left with a full of fuel may have been a good rust prevention measure

I have one of those camera jobs for my pc...I use it to peek in box sections, engines etc I am the owner of a TR6 so use in in the chassis too......I I have had to go the same route removing the sender, drilled out but had to re tap right through. I did try a number 3 tap but just could not get enough thread to be safe.
Its a silly arrangement, the ring is usually seam welded onto tanks and the bolts go right through......this ring is part welded so it will leak unless a good seal is made on studs from inside of the thin tin tank.......did yours seal up ok with bolts from inside and loctite?
which loctite did you use...green??
The sender I have actually made work!! the cover inside was removed to clean the muck off and improve contacts on the variable resister winding.
Then on the top with cleaning the centre stud remaining was found to be brass insulated by plastic from the main body. A wire easily soldered to the brass and will be tidies up with heatshrink and sealer. The earth will be tagged under one of the mounting bolts.
I had it on the car and the gauge reads up and down as it should.
Finally, regarding pump output other than the after market car it is stock I believe, The manual pump output test of 1100cc in a minute equates to just 66 litres or just under 15 gallons an hour though the filter and to the carb inlet at the correct pressure.

Hi Danny, I am looking at my tank and despite having small hands/fingers cant see any way of wiggling in and starting off the bolts from inside the tank to make studs for the sender unit? Did you find any trick or tool to help? I wish I had got studding and then applied nuts underneath!
Cheers

Now you mentioned the studding, that was the way i did it. I also tried the bolts from the inside...no go. Sorry i got you on the wrong track there.

well, I used the bolts....I cut a little slot on the end, held up against the tapped hole with one finger and started the thread with a wee screwdriver through the hole!! job done now.