Frugal or Fireball? Judge me for this EFI tank conversion idea

I am looking to convert Datansiti's fuel tank from carb to EFI using the donor car's internal pump. Planning to use aluminum hard lines from tank to engine for cheapness. I can make a hanger for the pump and attach it to the Datsun sender flange no problem. The trick is getting that darn line out of the tank. The correct way is to buy a bulkhead fitting, but after you've added up the nuts, fittings to convert back to hard lines, and barb fitting for connecting to the hose, you're darn near $40 bucks with shipping. That's a significant hit to a Challenge budget. Actually, the really correct way is one of those pricy in-tank conversion kits that comes with the mounting flange and all the right hardware and seals.

What if...I just welded a short piece of steel tube to the flange as a pass-through, with plenty of clearance internally for a normal hard line to fit through, then potted that connection with plenty of JB weld? I could use a plastic syringe to inject the JB weld deep into the gap. Then just use a simple brake/fuel line union to connect to the rest of the system. 

Or should I just stop being such a cheap-ass and order the right stuff.

I'm guessing the G35 system is returnless, so only one line to worry about?  How does the fuel normally get out of the Datsun tank?  I'd be looking for a way to use whatever outlet the tank already has, maybe just a couple pieces of cleverly routed fuel injection hose would do the trick?

So it would go fuel pump (inside tank) > EFI hose> fuel tank hardline (maybe you have to cut and add a barb to this)>  EFI hose> your new hard line 

Yes it's returnless, only one line. I would like to use the in-tank hard line, but I would need to split open the whole tank to access it. You can't really reach it from the sender hole, so installing the pump would be challenging. 

Also, how to get pump wires out, cheaply? They make a fancy $20 bulkhead fitting just for fuel pump wires.

How about using steel hard line for that stretch, and simply brazing it to the sending unit  flange? That's pretty much standard operating procedure for '60s and '70s era domestics.

For pump wires: Take a set of rubber grommets made from something that stands up to fuel, run a bolt through them, use ring terminals on each side. That's what I did when I converted my '72 Chevy truck to an in tank pump. Which turned out to be a bad idea in retrospect, but mostly because having a pump inside an in-cab tank is seriously loud.

Can the wires use the connector that was previously for the level sending unit?  If not, is it possible to drill holes in it and pot them there?

Unfortunate that the in-tank line doesn't work for this... in that case I think it would all come down to what you're going to pot/fill the gap with in your original plan.  You could test whatever it is by making a mockup (same materials and curing process) and submerging it in fuel for a while.

How does fuel get out now?

Use current fueling system to supply a "surge tank".  Use high pressure pump and corvette fuel filter from surge tank to engine.

Should work.

This is what we are doing for my buddies 79 RX7 that was carb and is now EFI.  Regular old facet pump feeding surge tank.  High pressure pump picks up fuel from surge tank to engine.  Engine returns to surge tank and when that is full, it returns to gas tank.

Check out this link for a more in depth look at how to make the surge tank out of a large filter: 

http://madscientistmatt.blogspot.com/2005/12/surge-overkill.html

corvette fuel filter:

https://www.speedwaymotors.com/Speedway-GM-LS-V8-Fuel-Filter-Fuel-Regulator-Kit-58-PSI,41791.html

Or, weld a JIC fitting to the very bottom of the tank and hook up AN line and feed an inline electric pump like an E2000 pump.

AFTER washing the tank out with Dawn dishwashing soap, Fill the G35 tank with water and hack out the area around the fuel pump. toss in a half box of bicarb if you are at all worried about stuff blowing up during the cutting operation. Will flood the tank with CO2

Cut a similar sized hole in the Wagon tank and solder (with a big non flaming soldering iron) the G35 chunk, including pump, into the hole. Keep adding solder until it is sealed. You can make one of these soldering irons from any chunk of steel and you just keep re-heating it as required.

In reply to NOHOME :

I watched my dad repair more than one tank that way when I was a kid.

NOHOME said:

AFTER washing the tank out with Dawn dishwashing soap, Fill the G35 tank with water and hack out the area around the fuel pump. toss in a half box of bicarb if you are at all worried about stuff blowing up during the cutting operation. Will flood the tank with CO2

Cut a similar sized hole in the Wagon tank and solder (with a big non flaming soldering iron) the G35 chunk, including pump, into the hole. Keep adding solder until it is sealed. You can make one of these soldering irons from any chunk of steel and you just keep re-heating it as required.

 

 

 

This was mostly my recommendation as well. 

My suggestion involved using an air chisel to do the rough cutting on the tanks. 

wvumtnbkr said:

 

Check out this link for a more in depth look at how to make the surge tank out of a large filter: 

 

http://madscientistmatt.blogspot.com/2005/12/surge-overkill.html

That has since been replaced with a sumped tank and single fuel pump. Instead of using some off the shelf weld on sump kit, I used a cake pan from Wal-Mart, since I was going to be welding anyway. I need to get the pictures of that up.

From a quick search, looks like I need OA torch to braze steel, which I don't have. I'm much more comfortable with TIG. Do you think I could just carefully TIG a 5/16 steel brake/fuel line to the flange? Put a flare on the internal side for short piece of hose to the pump, and put a union on the outside to the rest of the fuel line.

From my experience a surge tank is the best answer here.  Whatever solution you implement cheaply otherwise will result in you coming back and asking about how to get a sump/baffles into your tank to remedy the fuel starve issue you get with less than 1/2 tank of fuel.

maschinenbau said:

From a quick search, looks like I need OA torch to braze steel, which I don't have. I'm much more comfortable with TIG. Do you think I could just carefully TIG a 5/16 steel brake/fuel line to the flange? Put a flare on the internal side for short piece of hose to the pump, and put a union on the outside to the rest of the fuel line.

You can get TIG brazing rod...  Silicon bronze

Can you buy an Infiniti repair connector for the pump end? 

If so, could you use original metal line spliced to the connector? That’s what I did on my Fiesta. I also made a cup for the pump to sit in inside of the factory tank. 

This connects to the Fiesta factory metal fuel lines, and then to the Focus intank pump. We have a kit here at work that presses the fittings into the hard plastic line that I made this with. 

All great suggestions! Any other forum would say "just pony up the cash for a conversion kit you cheap-ass".

Something else to consider, I may need to "trim" the front side of the tank to make it fit behind the IRS I just installed. If I am going to hack up the tank anyway, I might as well split it open and add baffles and pump tray. 

Sounds like I just need to dive in and see what's actually feasible, but now I have more options on my mind to consider. 

You have a TIG?  Why not make an aluminum plate to screw to the top of the tank and weld the line to the plate?

I like the lift pump to surge tank idea more and more. Requires less modification of the Datsun tank and I don't have to worry about baffles.

Do we trust $10 eBay electric inline pumps?

I would cut the top out of another tank and then cot a corresponding hole in your tank. If you can tig well enough then just get the figment right and tig the NER to piece on and use the in tank pump that goes with the piece you cut out. If I was doing it I would just make the tank hole about a half inch smaller and then rivet the new top piece on and solder it in place.  I have repaired many tanks using solder and lap joints. You don’t have to braze it. 

However all that that being said why not use an external pump?  I would just do that by putting the pump back by the tank and run a return back to a t behind the pump and put a RRFPR on the return. That way you are ready for boost should you want to go that rout. For a pump I would use a Bosch out of a 944. I would use metal lines where possible as it would help cool the fuel. Especially on the return. I know not as elegant as a in tank but it eliminates all the messing with the tank. Basically it just becomes plumbing and getting power to the pump.