Drilling Holes in fuel tank

I need opinions on how to drill multiple holes in my fuel tank without blowing myself and my jeep to smithereens. The under seat fuel tank in my CJ5 was custom built by somebody. The floor has been cut out and the tank was extended down the side of the frame rail so it's shaped like an “L”. I can’t get the tank out of the Jeep unless I pull the body off the frame, not doing that. I would like to add a universal fuel sending unit to the tank because there currently isn’t one. I bought a sender and matched gauge so I just need to drill some holes and mount it. I have siphoned the gas out as best I can. My first thought was to remove the fuel line from the engine and fill the tank with water and let it pore out the filler neck while drilling. I was also told to use my truck exhaust and hose it into the tank and fill it with CO2. What would you guys do? Any other ideas?

 

If you put dry ice in the tank, the CO2 will displace the air. That's what the pros do when they cut into an underground fuel tank (at least that's what I've seen on TOH). Not a recommendation - just an observation. Don't use the truck exhaust - it may contain lethal levels of CO, but I expect it contains plenty of O2 as well.

 

Go with the water plan - fill it up completely and run it over as you suggested. Do Not rely on carbon monoxide - you may not live to regret it!

 

I've just flushed 'em with a garden hose and plenty of detergent; and keep it full of water while you work. Don't electrocute yourself with a power tool near the water. Dry it afterward with alcohol rinses. (...the tank, not you.)

Then I've seen our local mechanic soldering a leak in a full gas tank, under the vehicle. Claims if you are below the fuel line, it can't blow. PLEASE don't try this at home....

Ditto on the exhaust idea - I believe CO can be explosive at certain mixtures with air.

Good luck.

Pete

 

While I don't have the cajones to try it, your local mechanic is right. Gasoline doesn't explode - gasoline VAPORS explode. In the bottom where the liquid is, there's no vapor and, more importantly, there's no air to support combustion.

Still, yikes...

 

If it was leaking though, I'm not sure I would trust that there wouldn't be a high level of gas vapors comming from the leak... Just a thought

 

Should be fine with a drill, just be sure to grease the flutes of the bit to keep shavings out of the tank. IF you feel the need to rinse the tank, I would fill it with water 3 times, then 'poof' the tank with a match.

 

If it's a poof or a kaboom, does it make a difference to use a match or just wait for the drill to do it? It it doesn't kaboom why poof it anyway? Seems like checking for landmines by stomping with one foot...

Am I missing something?

Pete

 

Thanks for the ideas. I think I'll stick with the water.

 

I use a air hose with air moving the vapors out of tank . vapors come from the metal in the tank. As long as air the push out vapors no boom welded on tanks before with no problems

 

Just be careful we don't need ya wearing a fuel tank helmet!