EFI In-Tank Pumps and Welding Stock Gas Tanks. A Volatile Discussion.

[zKars]

Ok, I have a 71 240 that I'm converting EFI. This means using an EFI fuel pump.

My usual MO here is to retro-fit an in-tank pump. Quiet, secure, self filtering, blah blah blah. Done it to my old 73 years ago and to a couple of my 510's since. Easy peasy as they say.

Well the 510's are easy. Lots of room above the tank. Not so much on Z's. If you want to mount the pump in the top of the tank, there is no or very little room between the floor and tank top, and you have to cut a wee hole in your deck then come up with a way to cover it. Then put up with a lump back there for ever more. Not perfect.

Well until Vintage Tanks just announced a new product.

https://www.vintagetanksolutions.com/product/1970-1976-datsun-240z-260z-280z-poly-fuel-tank-for-in-tank-retrofit-fuel-modules

This is the "right" way to do for sure. They provide you a recessed area to mount the pump and sender flange. and its still 16 US gal. Slick.

The bad news of course is the cost. $800 USD plus shipping exchange, duty etc. Usually works out to double that in CAD by the time it gets to me. Ouch.... Customer project or not.

SO.....   This crazy Canuck wants to to make a recessed area on the top of the stock tank to accomplish the same thing. Just a little fabbin' and cuttin' and weldin' and BOOMin' and screamin' and scrapping Canuck body parts off the shop wall. Right?  Though shall not weld a fuel tank, pretty basic knowledge.

Surely there is a safe way.

 

 

 

 

Edited December 18, 2023 by zKars

[zKars]

I have taken past fuel tanks in for cleaning and repair and they "boil" the tank first, whatever that means.

Well in my area, there is only one shop that does this anymore and the cost is really silly. 

So let the crazy ideas flow. How would you do it?

Fill it with water while you're welding? Maybe. heavy, awkward.....

Air it out with hot air in one end and out the other for 3 weeks on a hair dryer?

Just light off the fumes and get it over with?

Buy a gallon or 2 or 3 of methyl hydrate or Lacquer Thinner and rinse it out?

Got lots of inert gas in bottles for welding so fill it with Argon? Cutting into it going to make sparks too....

Been sitting outside "Airing" out for 6 weeks already. Can barely smell anything....

Any other bright ideas?

 

Edited December 18, 2023 by zKars

[Mark Maras]

 Dry ice is the answer. Pour some into the tank and wait for the CO2 fog to come out the top. I watched (from a distance) when a crew used this method to cut (with a torch) into an underground gas tank they had pulled up onto the surface.

[Zed Head]

The gasoline does not soak in to the metal.  If you fill the tank with water once and empty it it will be purged of all flammable material.  Gasoline is partially soluble in water, so any crevices, cracks, or rusty spots will be extracted of their tiny amount residual liquid gasoline.

Dry ice would work well too, after all of the liquid gasoline is removed.  If there is liquid left in the tank the CO2 will push out the vapors but the liquid will revaporize once the CO2 is gone.  One reason that CO2 works well also is becuase it displaces the oxygen.  No oxygen, no flame.

But CO2 is also dangerous for that reason.  Closed spaces and all that, plus the possibility of freeze-burns.  Water is cheap, safe, and easy.  The hardest part is getting the insides dried out afterward.  I'd just use water.  CO2 is great for underground tanks because they're big and you'd have to pump out the water if you used it.  But a Z tank can be tossed around pretty easy.

Why is my spell-check not working anymore...

p.s. I've taken some classes where these types of subjects were studied.

 

Edited December 19, 2023 by Zed Head

[zKars]

Great advice. Thank you!

I did find a video where they used steam. Heat accelerates the evap and water does as you mentioned above. 

Maybe this is what “boiling the tank” is meant as in a rad shop. 

It will be a bit before I get to this, but will attempt to remember to post pictures when I do it. 

 

Edited December 19, 2023 by zKars

[Patcon]

Maybe they're using really hot water? That would explain the work description

[grannyknot]

Jim,

 

[Patcon]

25 minutes ago, grannyknot said:

Jim,

 

Who welded it?

Mig or Tig?

Any leaks or post weld sealer?

[heyitsrama]

I wonder if a large metal trash can could hold the tank, you could then fill it with water and put a little gas burner under it... Get it to boil out any residuals...

[grannyknot]

9 hours ago, Patcon said:

Who welded it?

Mig or Tig?

Any leaks or post weld sealer?

Mig, I did the welding, lots of tiny spot welds until I plugged them all up then coated inside and out with POR15 gas tank kit.

[zKars]

Yeah, see? That’s what I’m talking about. Nice work Granny. MIG is fine especially if you seal it well. A pass with the TIG torch on the MIG bead can also help to homogenize the weld and remove pin holes. 

Maybe not quite so deep, the Holley in tank pump I’m using is maybe 3/4” or an inch high above the top. 

This will also allow me to bias the location away from the stock sender so I can retain it. When you put these things on top of the stock tank, the only flat spot up there puts the guts of the pump hanger perilously close to the sender arm….

[Namerow]

Nice work, for sure. Were any precautions* taken before you started cutting and welding?
(*see Jim's list of possibilities in Post #2)