Is a fuel return line needed?

[Sid]

I'm building a 64 Studebaker Avanti R2 clone engine and I'm switching it from mechanical to electric fuel pump (4–12psi). I will also be running a Paxton supercharger and installing a boost reference regulator. My question is, with such low psi, is a fuel return line necessary?

Thanks,

Sid

 

[Rust in peace]

I always run one. I like the idea of letting the fuel cycle as the engine takes what it needs as needed.

The only system I had set up with a deadhead was 6 lbs. of pressure and the electric pump quit working prematurely. Maybe the pump failure was not related to the deadhead pressure but when I reworked the system after replacing the pump and adding a return line it has worked flawlessly now for seven years.

Sometimes it is a pain finding room for the additional line.

Don

 

[zzrodder]

With a carburator, you need good GPH flow but not high pressure and with the blower, the GPH needs are higher. A lot of mechanical pumps use a return line to keep the pressure balanced and it's probably a good idea with an electric pump too even though you're not running high pressure. As I recall, a lot of carbs don't like over 5-6 psi as it can overload the needle and seat. I expect your regulator would have to have a bypass port to connect the return line to.

 

[burnin#2]

it will depend on the type of pump you use, hopefully you still have the instructions..... i know thats usually the first thing to hit the trash pail when i get a new toy but in this case it should be of some help. if its a electric plunger type pump a return is not nessisarilly needed but if your using a vane type pump with a higher output volume (because you using a huffer) a return will be needed. a return is needed with any positive dislpacement pump (vane or gear) to keep the fuel flowing and in turn keep the pump cooled and lubricated correctly

 

[donsrods]

This was just debated on another forum I am on. I have never used one and have run probably 15 electric pumps over the years, some on my daily drivers. Some people do run them though. I have seen no adverse affects by not doing it and will continue to not run one.

Don

 

[sgtpontiac]

Just my 2 cents on this topic....

On of the main reasons for Bypass/returns on stock manual fuel pumps was to help stop vapor lock.... boiling of the fuel from heat in the fuel pump and lines...... I believe that the first ones were done when they started to have so many accessories on the engines, the engine compartments got tighter/fuller and that the underhood temps went sky high and they had the vapor lock issues.....(us old guys know what vapor lock is) if you don't have high underhood temps then you probably don't need one... Electric pumps, the high pressure ones(like on the efi engines) would puke without one and the low pressure ones 6 to 14 lbs don't seem to mind not having one..... at least that's been my experience..... never used a bypass on any of the ones I've used on carb set ups.....

 

[Rust in peace]

Here is as much info about fuel systems as you will ever need. Enough to make your head spin. (at least, some of us)

If you don't care about high performance then you probably shouldn't waste your time.

But if some are like me, I want all I can get.......

http://www.centuryperformance.com/f...tanding-fuel-pressure-and-volume-spg-140.html

Don

 

[PA41]

An easy way of doing a return is pluming a T in the line from the tank to the pump. Serves the same purpose as a return to the tank, just is simpler and uses less line.

PA41