Loop Lines?

Sorry if this is a basic question, but I've heard and read two schools of thought.

This is in relation to putting the 4-way below the fuel pump inlet, and running your high speed and 3-way bypass returns to the pump inlet.

I have heard both that it doesn't hurt anything, and that yes, it hurts a lot by disrupting the fuel flow into the pump.

Yes, no, maybe?

What about running the main return and 2ndary return into the pump inlet to simplify plumbing? Yes, no, maybe?

Just looking to clean up some plumbing, and maybe lose some weight.

Thanks in advance.

-WJ

 

Myself and many others I know use the loop method on return lines. I personaly only put any return lines into the suction manifold or line no closer than 12 to 18 inches from the pump and angle the weld on fittings at about 45 deg. in the direction of the flow. Any loop from the shutoff probably does not matter as there would be no flow during a run.

 

It depends on which returns you want to send to the inlet, a pump sizer or main is OK, but a high speed needs to go back to the tank.

EDB

 

Eric
Why the high speed back to the tank but the others its ok?
Thanks

 

I have always ran my pump loop back to the intake side of the pump and I run all the other returns back to the intake side of the pump also. I run a fuel log off the shutoff with the high speed, pump saver, low gear lean out and the shut off running through it. Then all these go back to the intake side of the pump. It is simple and minimizes a ton of plumbing. Lots of guys run it that way. Folks have some idea that these return lines carry a bunch of air with them and that would cause problems. But I don't believe they do. I used to run all the return lines back to the tank but I haven't seen any difference with doing it this way. No reason to over complicate things. Dave Germain

 

I also have run all returns to the fuel pump without any trouble , just remind yourself to pen all leanouts ect (make them flow) at your warm-up . That way all the air will be out of the system when you run . By the same way whatever air is taken during start-up will be purged by the main jet .

 

Dave, would you mind sharing a picture of this setup? It sounds like a good idea

 

Dave,

Like the other poster, I would also like to see a photo of your setup if you don't mind.

If you're running everything to the pump inlet, do you even run a return line back to the fuel cell?

Do you run a data logger? If so, did it provide the information to you proving that it made no difference?

My biggest concerns were:

1. Disrupting the fuel flow into the pump by having extra fittings directly prior to the pump.

2. Changing the jetting due to vacuum created by the pump.

3. Aeration (as you have already mentioned).

-WJ

 

this should help on the visual.....

 

Sure does, thanks.
I hate asking questions, but you don't learn if you don't ask.
From the pump to the right...
Main Return, 2ndary, high speed?
If so, what exactly is coming out of the left side of the pump itself with the poppet?
Who sells that fuel log you're using?
-WJ

*edit* NM on the fuel log. Found it on RBS.

 

That is the pump sizer.

 

Here is a picture of my deal, stack injected,
BY Spud Miller @ FIE
I send the main and HS back to tank,..the fitting
at the top right w/red cap is the secondary by pass,
which helps feed the pump loop,
..on the left
pump sizer,.HS lean out,. and Main.

 

So on the blown app you run the High Speed and main into the pump, but on the n/a motor you run it back to the tank? Now I'm really confused.

I think it's time to call Bob Szabo and get his book on the way. I'm really looking at stepping up this year, and I don't want to go hurting a ton of parts in the process.

-WJ

 

on this one a Hillborn stack injected deal there is only one
return type fitting on the barrel valve,,...
on the blown deal there are multi return fittings on the barrel valve,
..on a n/a application how you have it plumbed can vary
due to size of the pump and fuel system gpm, and desired pressure
to the barrel valve.
its really not confusing.

 

also,.. take into consideration that a Blown motor
is going to be using alot more fuel than a N/A motor
thats partial reason for the two returns to my tank, as
appose to a blown motor putting it right back into
the inlet side of the pump.

 

Ah, this makes sense. I've not messed with MFI on non-blown apps, so I've not researched the associated barrel valves to know there weren't more returns.

 

Standard N/A barrel valve 1 in and 1 outlet

typicle enderle K STYLE BARREL VALVE FOR BLOWN

 

The theory is that the HS may not open on the burnout and may allow some air into the inlet of the pump during the run causing a lean condition.

Not everyone believes this theory though and that is OK.

EDB

 

Wouldn't this show up on a data recorder?

-WJ

 

A data recorder for fuel,..(flow meter) will record fuel
going into a motor after the barrel valve,..not how much fuel is
being returned which is at the BV in a standard set up.