Adding a return fuel line to factory tank

[mike's1965]

I bought a Edelbrock Pro Flo 4 multi port fuel injection for the 396 in my truck.

Also waiting for the sump fuel pump to be processed and shipped, it's currently a free rebate until end of October if you buy any pro flo 4, it allows you to keep your stock tank, and uses your mechanical fuel pump(or electric pump for carb) to supply fuel to the mini sump with a electric fuel pump inside sump submersed in fuel, then pumps that up to whatever pressure you set for pro flo, or other fuel injection setups.

The sump kit requires a return line to fuel tank, according to tech support at Edelbrock, it's because the pump can warm up the small amount of fuel, and if it gets pressurized from heat, it needs to be sent back to tank for safety reasons.

My truck still has the tank behind the seat, where would be a good location to add a return?

I was thinking possibly through the sheet metal of the sending unit.

[mike's1965]

It appears a 1972 C10 fuel sending unit has a return line, would this fit on a 1965 C10 tank?

I'm sure the ohms are different for the gauge.

[jayoldschool]

There are a few threads right on here for installs for a return line on the sender. Use the google search up top to check them out.

[Mack B]

Originally Posted by mike's1965

I bought a Edelbrock Pro Flo 4 multi port fuel injection for the 396 in my truck.

Also waiting for the sump fuel pump to be processed and shipped, it's currently a free rebate until end of October if you buy any pro flo 4, it allows you to keep your stock tank, and uses your mechanical fuel pump(or electric pump for carb) to supply fuel to the mini sump with a electric fuel pump inside sump submersed in fuel, then pumps that up to whatever pressure you set for pro flo, or other fuel injection setups.

The sump kit requires a return line to fuel tank, according to tech support at Edelbrock, it's because the pump can warm up the small amount of fuel, and if it gets pressurized from heat, it needs to be sent back to tank for safety reasons.

My truck still has the tank behind the seat, where would be a good location to add a return?

I was thinking possibly through the sheet metal of the sending unit.

Here is a picture I snagged off a build thread here. Wish I could remember whose it was or details about it, but maybe it will help.

[mike's1965]

I found something else that might work, but not sure if it's the same diameter or if there is even room to add this Moroso kit, thank it would work?

https://www.summitracing.com/parts/m...QaAvW7EALw_wcB

[sstock]

Originally Posted by Mack B

Here is a picture I snagged off a build thread here. Wish I could remember whose it was or details about it, but maybe it will help.

The person that put that together gets props from me, great workmanship and the tube bending work is exceptional.

[nsb29]

My 65 w/ in tank pump not finished

[T Herder]

From 2011 post:
Here's the procedure I did when I fuel injected my 305
e V6.
Buy a new stock replacement fuel pickup and sending unit. Carefully remove the sending unit. Sand an area of approximately one inch diameter to bare metal on both sides of the new units mounting plate. Drill a 3/16” hole in the mounting plate and removed any burrs. Support the mounting plate on the internal side of the plate with a 9/16” six sided socket, the six sides towards the mounting plate. Take a 5/16” diameter tapered drift punch and drive it through the hole to form a tapered flare recess. This recess will be on the outside of the plate. Using a tubing bender, bend a 5/16” steel tube to parallel the fuel pickup line ending at the same bottom level BUT returning to the OPPOSITE side of the tank. Bend the external side of the return tube down to parallel the feed line. Carefully work the new return line through the 5/16” hole to what you THINK might be its final position. Then try fit it into the tank to confirm it will install with no problems. Once this is accomplished, Silver solder the 5/16” tube into the mount plate using 45% Silver solder.
If you’re hesitant to try this, practice first with a piece of scrap sheet metal and scrap tubing of the same gauge as your new replacement mounting plate.

Best regards,
Butch

[LostMy65]

Originally Posted by mike's1965

I found something else that might work, but not sure if it's the same diameter or if there is even room to add this Moroso kit, thank it would work?

https://www.summitracing.com/parts/m...QaAvW7EALw_wcB

Did you end up going with it?
It looks likes a pretty simple solution.

[mike's1965]

No, seems it is not the same size as the factory hose and pipes from googling hose sizes online, still might work.

Ended up buying a barbed end bulk head fitting, thinking it may fit on fuel sender, just need gaskets to seal it.

The truck has other bugs/issues I'm working out before getting into the swap.

[LostMy65]

Found this interesting:
https://help.summitracing.com/app/an...return-line%3F

[LostMy65]

I'm thinking of something like this, but I'm not sure if the hose is ethanol resistant.
Everything I do from this point forward I want to be ethanol resistant. Beings ethanol seems to be inevitable.
I'm thinking something as simple as dorman nylon fuel line from the fitting to the bottom of the tank.
https://www.summitracing.com/parts/f...0aAtXdEALw_wcB

[LostMy65]

Or something like this, but route the steel line a little further away from the pickup.

[mike's1965]

That's good information.

I was told by a company that makes fuel injection tanks and pumps you cannot use a bulkhead fitting on a fuel return or tank as it would leak.

The only way I can see it leaking is gas sloshing around and seeping past the metal washer inside the sender sheetmetal, my idea is rubber washers on inside and out side then the metal washers, in fact I have A/C line seals left over from compressor replacement on my Corvette, it came with a big bag with several seals that are metal and have rubber coating.

Maybe it will work, maybe not, I'm going to try on my old sender, that doesn't work once it gets to 1/2 tank, as level goes down more, still reads 1/2.

I have a pic but guess can't post it here without it having a link, the barbed bulkhead fitting is the size Edelbrock recommended for the vent line, the fitting's biggest diameter is about the width of my pinky finger tip/joint, seems like there should be room on the sending unit sheet metal.

I'll remove sending unit, clean or let it dry enough so no fumes, then drill the hole.

Thinking of running some metal fuel line for the majority of the run, then shorter pieces of hose on the ends, to try to eliminate any kinks or other issues.

[mike's1965]

Are you running a return or vent line back to the tank inside cab?

Also are you using the Edelbrock sump fuel pump, or what are you doing with your truck, fuel injection etc?

[LostMy65]

I have a fitech throttle body with the sump fuel pump.
Eventually I may install a rear tank. But my in cab tank is still in great shape, and adding a return line to the existing tank is the easier route for me right now.
.
As far as using rubber washers, For me, I'd be concerned how ethanol resistant they are.
I'm thinking nylon washers.
.
I can't see anything wrong with a bulkhead fitting with the right washer gaskets.
Besides, if it leaks, you'll know right away by the gas smell.

[LostMy65]

Might be of interest
https://www.google.com/url?sa=t&sour...=1585421961491

[mike's1965]

I can't view it.

Can you get those nylon washers at hardware stores?

[LostMy65]

Originally Posted by mike's1965

I can't view it.

Can you get those nylon washers at hardware stores?

Try this opening this attachment

[LostMy65]

Originally Posted by mike's1965

I can't view it.

Can you get those nylon washers at hardware stores?

Farming implement stores also.

[LostMy65]

Originally Posted by mike's1965

Can you get those nylon washers at hardware stores?

I'm thinking now that the washers alone won't seal it. We need something tight against the bung itself. I'm thinking something like this:
https://m.autozone.com/sealants-glue...0aAhG5EALw_wcB

Or this:
https://www.summitracing.com/parts/e...EaAqi9EALw_wcB

[mike's1965]

Tight against the bung?

I'm thinking a washer on each side, tightened careful so no distortion/wrinkle or tear, the compression should keep it sealed, however having no experience, it's up in the air.

Probably good idea to keep fire extinguisher in cab just in case.

That gasket on the sender holds the gas in, maybe washers can too.

[mike's1965]

Actually, maybe that permatex stuff would work good, just enough to lightly cover the inside parts of washers.

Maybe smear on a light coat on both sides of the new sending unit gasket also.

By the way, on Edelbrock pro flo forum, it was mentioned that 99.99 percent of the time it's for vent pressure, so a fuel hose or pipe going inside the tank isn't really needed.

[mike's1965]

On LMC truck thought I found the solution, says they have a fuel sending unit with a quick connect to help with fuel injection conversion, also says the replacement tank has a bung for return.

Called in and asked lady about sending unit, she didn't seem to understand and said she would email me a pic of it, well the picture I got just looks like a regular sending unit.

This one costs more than the regular, so I'm not sure what is going on, also on the picture it says for LS swaps.

[LostMy65]

Came across this:
https://youtu.be/W_swURooqVQ