610 fuel tank question

[datsunfreak]

On the tank itself, it looks like the smaller pipe on the bottom is the feed and the bigger pipe is the return? Can anyone confirm?

 

On my tank at least, it appears the small one just goes in a few mm and stops, and the big one goes in a ways then tuns to the side? Also, I tried filling it with water and the small line started draining it out immediately. The big line just dribbled a bit and didn't even do that until it was almost 1/4 full of water. 

 

Help! 

 

If indeed the small line is the feed, then someone has the lines hooked up wrong and the tank was drawing from the return line all this time, constantly leaving 1/4 left in the bottom, which would definitely explain all the sludge in the tank. 

[sssr20det510]

On the 510 tank the small one is the feed so i would imagine its the same

[datsunfreak]

On the 510 tank the small one is the feed so i would imagine its the same

 

Having owned 20+ 510s and this being only my second 610, I was thinking the exact same thing.   :rofl:

 

Just hoping some of the 610 gurus will tell us we are right.   :thumbup:

[datzenmike]

The larger one is always the return.

[datsunfreak]

The larger one is always the return.

 

If that's the case (and I have no reason to believe it isn't), then someone in this car's past screwed up big time...

[datzenmike]

It will still work but most return lines are always larger. Even the power steering return lines are larger than the pressure side.  Larger reduces the chance of resistance to flow. The pump doesn't have to pull and push fuel.

[datsunfreak]

It will still work but most return lines are always larger. 

 

I'm 99% sure the return line goes a it deeper into the tank. If you use it as the feed line, when it gets down to roughly 1/8 tank you will "run out of fuel". 

 

But that's if you're talking about the nipples on the tank, not the actual lines under the car. 

 

When I got this car the return tank nipple and chassis line were connected to the fuel pump, and the return from the engine was connected to the chassis feed line and tank nipple. 

[hosestop@msn.com]

Hey John I usually weld up smaller metal line and use the bigger one or cut off and weld(DO NOT WELD GAS TANKS I prep much and leave a bunch of air running through to avoid bad things)5/16 line for return on FI. cars and for feed on 610 used drain hole !in spare tire area ,510s do not have this, drilled out to 9/16 I think, re-tapped for a 90 deg.  3/8 = #6  O ring seat fitting with a nut like a bulkhead fitting to adjust height of fitting in tank .Will try and post if int. on 610 build.

 

Here is something to think about -I have seen Sr20dets and KAs swaps done by a shop cheap! here in So Cal ,that feeds swaps on stock 510 fuel lines ,they just throw a fuel pump where battery was and run it , crazy but as always you get what you pay for!

[datsunfreak]

Hooked up the lines the "correct" way and it was as we suspected. Fuel starting coming out of the small nipple immediately and didn't come out of the big nipple until it had at least 2 gallons in it.