[ZeGermanHam]

Hi all,

As I'm inching ever closer to the finish line in restoring my '66 GTO, I'm starting to think about what I'll need for my fuel system. I need to buy a new fuel tank, and although the car will be driven with a Holley carb for a few years once it's back on the road, there is a good chance I will want to switch to EFI at some point in the future.

So rather than initially buying a tank suitable for a carb w/mechanical fuel pump for the near term and then having to by a second tank that is suitable for EFI w/in-tank electric pump, does anyone know of a low-pressure in-tank electric pump that could be used in an EFI tank while I'm running a carb?

Thanks in advance!

[MNBob]

I used this one and now have converted to a Sniper:

https://www.holley.com/products/fuel...s/parts/12-129

[max 93]

https://www.tanksinc.com/index.cfm?p...id=-1&mode=cat

[grivera]

You can use a high pressure pump and use a universal bypass regulator like an Aeromotive 13301 or Trick Flow TFS-27001 (same as/made by Aeromotive). It comes with high and low pressure springs to do either carb or efi. In this scenario you run a supply to and return line from regulator. I did this with my q-jet using a Walbro 255lph and 1/2” supply/return lines. Later I added a Sniper EFI.

[ErikW]

I used a Vega fuel pump when I converted my dually from 350 TBI to 502 w/ carburetor. Kept the 850 Edelbrock carb happy. Carter part number P60293 at Rock Auto for about $27. No regulator necessary

[Formulajones]

Originally Posted by grivera

You can use a high pressure pump and use a universal bypass regulator like an Aeromotive 13301 or Trick Flow TFS-27001 (same as/made by Aeromotive). It comes with high and low pressure springs to do either carb or efi. In this scenario you run a supply to and return line from regulator. I did this with my q-jet using a Walbro 255lph and 1/2” supply/return lines. Later I added a Sniper EFI.

This ^^^


It's how I set up every in tank fuel system, it's very versatile.

[ZeGermanHam]

Originally Posted by grivera

You can use a high pressure pump and use a universal bypass regulator like an Aeromotive 13301 or Trick Flow TFS-27001 (same as/made by Aeromotive). It comes with high and low pressure springs to do either carb or efi. In this scenario you run a supply to and return line from regulator. I did this with my q-jet using a Walbro 255lph and 1/2” supply/return lines. Later I added a Sniper EFI.

Originally Posted by Formulajones

This ^^^

It's how I set up every in tank fuel system, it's very versatile.

Is there any downside to running a high pressure pump like this? Might be a stupid question, but if you're pumping that much fuel and most of it gets diverted straight back via the regulator, are you heating up the fuel in the tank more than you would if using a low pressure fuel pump?

[Scott65]

Yes, you can heat the fuel. There are fuel coolers that can be plumbed into the return. You could also locate the regulator close to the tank. The right size pump is the best option though.

[chuckies76ta]

Originally Posted by ZeGermanHam

Is there any downside to running a high pressure pump like this? Might be a stupid question, but if you're pumping that much fuel and most of it gets diverted straight back via the regulator, are you heating up the fuel in the tank more than you would if using a low pressure fuel pump?

I would do as Post 4 advise. Set your fuel system up for your future plans and that part is done. All that will be required is a spring change on the regulator. I'm not convinced that the fuel will be heated up to cause any issues on 6 or 7 psi. I understand what Scott is referring too. Using a high pressure pump then chocking it down to 6 psi causing a restriction. The fuel restriction should only affect the line to the carb and not the supply and return lines. They make these regulators to do this exact job, so I can't see any issues. Thing is the fuel in the tank is cold and will be returning via return line constantly when running . Remember that the fuel pump is also cooled by fuel in tank. I have a friend running a high pressure in tank pump with carburetor engine with no issues on street or strip. JMO.

[OCMDGTO]

X10 use the EFI in tank pump with a bypass regulator to feed that carb. I have the Tanks 340lph pump and a Weldon Regulator mounted near the carb. Great system

[Half-Inch Stud]

Originally Posted by ZeGermanHam

Is there any downside to running a high pressure pump like this? Might be a stupid question, but if you're pumping that much fuel and most of it gets diverted straight back via the regulator, are you heating up the fuel in the tank more than you would if using a low pressure fuel pump?

Engine fuel-use rate is same same for Injection or carbination

[leeklm]

Around 1990 we put a carburated SBC in my 87 S10 daily driver. My buddy was a GM mechanic and knew of early 80's cars using an in-tank low pressure pump with no bypass. I want to say we used the pump, relay, etc from an 82 or 83 Buick. I had a pump go out within 5k miles, but the next GM replacement pump went over 100k.

With that said, I would definitely go the route as recommended below of a high pressure pump and bypass regulator. While you may heat the fuel a little, it is also cooling back down via the bypass. I have been running this way for several years with no issues.

Then when ready for EFI, there is no reason to drop the tank! Good luck with the new build.


Sent from my SM-G965U using Tapatalk

[Overkillphil]

I’ve been using an EFI in-tank pump (255 l/hr) for well over 10 years with a Qjet and never had any “fuel heating” issues. It’s not even on the radar and this is the first time I’m even hearing it mentioned. The regulator is dealing with pressure, not flow. The fuel consumption rate is similar anyway so once the operation pressure is achieved a similar amount of fuel is returned to the tank whether it be EFI or carb in this case. Don’t over think stuff.

[Scott65]

There's no concern over "restriction" the potential issue is all of the fuel that is not consumed by the engine is returned to the tank AFTER being exposed to the underhood heat. That's why one of the solutions is to mount the return regulator close to the tank. I monitor fuel pressure temps on mine, I know for certain that fuel can be heated this way. Will it be too much? Depends on the situation. Mine gets up to 127° in the summer heat, closer to 100° in cooler weather. I run efi, at 43.5 psi. Look at the pump curves for the different pumps on the tanks site. Pay attention to the flow at the different pressures. Proportionally, a lot more fuel flow at low psi, equates to more fuel to return at carb pressures. To the OP, use the aeromotive regulator mentioned, as it's good for both efi, and carb duties. If you use a tanks style tank, and end up with fuel heating issues with the 255lph, they offer both style pumps, so you can swap to the carb version pump they offer and save the 255 for when you go efi.
Separately, another great alternative to do this is pwm control of the pump. However you'd need to go with a turbine style pump for that, as it's unsuitable for the gerator style. It will pulse the pump at very low duty cycle so you don't have to return as much fuel.
Hopefully you'll be lucky, and get away with the simplest version as others have posted about. Although I think some just don't know they're heating the fuel.
ETA: my observed fuel temps are WITH a cooler in the return line.

[Steve C.]

Might be of interest...

Why Do Electric Fuel Pumps Die?

https://www.hotrod.com/articles/why-...uel-pumps-die/


.

[grivera]

Originally Posted by Steve C.

Might be of interest...

Why Do Electric Fuel Pumps Die?

https://www.hotrod.com/articles/why-...uel-pumps-die/


.

Good article but doesn't make a distinction between in-tank vs external fuel pumps, but seems to be about external which would be more susceptible to issues mentioned..

[Scott65]

All the issues apply to both. The inlet size issue is predetermined on the in tank pumps though.

[Formulajones]

Originally Posted by ZeGermanHam

Is there any downside to running a high pressure pump like this? Might be a stupid question, but if you're pumping that much fuel and most of it gets diverted straight back via the regulator, are you heating up the fuel in the tank more than you would if using a low pressure fuel pump?

Heating fuel can be an issue but I've never personally experienced it with these systems. Most of that I've seen or heard about are on pretty serious cars with serious fuel systems trying to feed 1500hp drag week cars that are running small 10-12 gallon fuel cells in the trunk, with giant external electric fuel pumps. Not a lot of fuel to go around to begin with, and an external pump on top of that gets pretty hot on it's own.

An in tank system with 20 gallons of gas in a 700 hp street car, even with a pretty big 450 LPH pump, I just haven't seen it.

What I have had issues with are running systems with the return line very short at the back of the tank. Especially when regulated down to carb fuel pressures. The feed line fuel tends to sit more stagnant and absorb more heat and with low 6-7 lbs. of fuel pressure I've had some issues with heat soak.

When I move the regulators close to the carb and run a full length return line, most of that fuel is heading back to the tank, where it mixes with the cooler fuel in the tank. That seems to have solved any heat soak issues I've seen with carbs.

On EFI it's not much of a concern either way because you're running upwards of 40 to 60 psi fuel pressure. Fuel at that pressure is less prone to vapor locking and guys have more luck running short return lines with regulators at the tank. However I still run the full length return on the EFI stuff here just from my experience with carbs. Might not be absolutely necessary but it doesn't hurt either, besides it was already plumbed that way before the EFI conversion anyway. Simply change the spring in the regulator and it's ready to rock.

[Formulajones]

On the inlet sizes, Walbro does make a series of in tank pumps that have larger inlet openings if you prefer or need it. I forget what that series is called at the moment but they can be found on their site.

[grivera]

Thanks FJ - I too run 1/2" supply and return to regulator in engine bay