In the IVA section you will see that I had my test today and failed on three things. One that I didn't fail on because it wasn't spotted at the time was that the fuel tank has a slight weep from a pin hole in one of the welds (We spotted it whilst changing some of the electrical connectors). I could not have spotted this before today as its the first time that the tank has been full. Clearly it needs to be fixed whether its spotted at the retest or not.

I want to avoid taking the tank out if possible as it will involve taking half the car to bits and then will need to drain it etc. Is there anything I can use to paint over the pinhole to permanently seal it. Its fairly high up so I can siphon fuel out to below the hole. Clearly naked flames etc are out.

PetroPatch (if it's still avilable) should work. I've alsodone temporary seal to a leaking sender unit that wasn't as temporary as I first thought and was still there 2 years latter using chemical metal putty (sorry sorgetit's real name).

I'd avoid the paint like stuff you can put inside (used byclassic restorers) or any silicone/PU as they tend to react to fuel.

Any good?
http://www.shop4glue.com/fuel-tank-sealer-for-motorcycle-bike-car-lawnmower-petrol-diesel-alcohol-fuel-leaking-repair-rust-612-p.asp

or maybe Chemical Metal (which I believe is fuel resistant)

I used tank sealer that you pour into the tank and move about to seal all the welds after I made my tank for the land rover. This worked well for about 4 years until the sealer started to flake off into nice pick pipe sized chunks. Still not resolved this but as a temporary (2 year now) measure I put some wire mesh over the pickup pipe which seems to work well.

This one? linky
HTH.
Cheers, Pewe10

Thanks. I've drained the tank to below the hole. Other half now has a free half tank of fuel.

I'm going to try quicksteel first as I really don't want to have to remove, drain and vent the tank. Its only a small pin hole where one run of weld ended and another began - only one drip every 10 minutes or so. Should be an easy fix (hopefully)

I would try penning the metal first with a small hammer.

Would it be possible to solder the hole up? A powerful soldering iron might do the trick. Its less than 400 degrees IIRC. Or would this ignite the fumes in the tank? I doubt it. But try it at your own risk etc..

Nothing quite as permanent as Gunson's Petro patch. I used it as a sealant on the top of my Aluminium tank where I bolted the steel adaptor plate (cut out of a standard ford tank) to take/fit the standard Ford fuel sender unit. (with a cork gasket as well).

Edit bit £5.99 on Amazon. Other suppliers ARE available.
Linky dinky

[Edited on 4/4/14 by jollygreengiant]

Another vote for petropatch if you can find some