Scratch Start Tig On Sheetmetal

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I'm interested in setting up my idealarc 250 AC/DC for scratch start and I'm wondering what is the thinnest metal I'll be able to weld with it.  I may be making some modifications to a fuel cell and I would like to Tig it to reduce the possibilities of leaks.  Is this something that I could reasonably do with a scratch start tig or should I be looking for an Oxy/Acetylene torch setup and do it with bronze instead?  I haven't used a scratch start setup before so I'm not certain of it's limitations.  I have gas welded, just not in a couple of years.  My last gas welded project was a custom exhaust for my old Honda dual sport.
Reply:There really isn't a thickness limitation when working with a scratch start setup, but the thinner the material the steeper the learning curve. What type of fuel cell are you modifying and what sort of modifications are you performing?
Reply:I'm going to be modifying a 1981 CJ7 fuel tank to accept an in tank fuel pump.  I'm considering either grafting on the portion where the pump and vents and return attached, or taking a newer tank with the pump and narrowing it on one side.  I have considered an external fuel pump or a completely new fuel cell made of 1/8" on three sides for strength and 1/16" on the left/right/top sides.  Problem with the external pump is that I still need a return and a vent to meet smog requirements so I'll probably end up attaching some type of fitting to the tank.Another project is to make a fuel pump cell for a motorcycle fuel injection project.  The problem is pretty much the same as the jeep, just on a smaller scale.  To inert the tanks I've found that several rinses with simple green is effective at greatly reducing the chance of explosion.  Also I start the cut by drilling a large hole with flood coolant and then use a reciprocating saw to actually cut the tank just to make sure.  So far I've done this with 3 tanks without any problems during the cutting or welding.  The last one I welded I used a mig welder but I can't say that I thought highly of the process and tracking down pinhole leaks.
Reply:Is there any way you can remake the fuel level sending unit bung plate to achieve what you're trying to do? It would be much safer, and that's how alot of newer vehicles are, pump, sending unit and outlet/return all in the same plate.
Reply:I think the bung plate is too small.  It is about 1-2" smaller in diameter than the new fuel pump.  Maybe though I could add a return and a vent to it.  I'd need to run the return through a hard line back to the bottom to prevent air in the fuel.  A scratch start tig is similar in cost to a small portable used torch set around here.
Reply:Looking online I've found some guys that have mounted a pump on the stock pickup.  Im going to see if the explorer plate and pump could be made to fit. Sent from my iPhone using Tapatalk