Regulated return vs regulated feed

00Powerstroke · Aug 20, 2013

looking at LPFS's for my truck i noticed different kits that are sold by various vendors have all kinds of differences, like you can run a regulated return and some rune regulated fuel feed to the HPFP or the fuel bowl depending on your setup. What I would like to know is the benefits and just understand it better.

Thanks,
Henry

one2nine · Aug 21, 2013

Your regulator to the hpfp should be set by your pump then most run a regulator at the fuel block for the return.

00Powerstroke · Aug 21, 2013

one2nine said:
Your regulator to the hpfp should be set by your pump then most run a regulator at the fuel block for the return.

So your saying the HPFP should regulate itself with its own internal regulator and at most run a regulator the the return fuel? Now I dont understand the point of regulating pressure on return fuel

one2nine · Aug 21, 2013

The computer regulates how much fuel the hpfp needs to put out. You're simply supplying the hpfp with a set rate from your air dog (or whatever lpfp) you run

simonton6.4 · Aug 21, 2013

I'm not sure and someone can chim in and correct me but your lpfp should be setting the pressure going into the hpfp (15psi) then a reg on the return will help to set the pressure in the hpfp that's the way that I have understud it not sure if this answers the your question hope it helps

Dzchey21 · Aug 21, 2013

15 would be on the high end. 10 psi is about all you want

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00Powerstroke · Aug 21, 2013

one2nine said:
The computer regulates how much fuel the hpfp needs to put out. You're simply supplying the hpfp with a set rate from your air dog (or whatever lpfp) you run

This is a very broad statement, obviously the computer controls the hpfp but how does it control incoming fuel? and according to my diagrams the k16 pump has a internal pressure control valve, is that for high pressure or the low pressure fuel coming in?

so going into the HPFP from your lpfp you want about 10 psi, is the only way to achieve this pressure to regulate it coming off the lpfp? I plan on using a Aeromotive a1000 pump.

I understand regulators but as far as how it works with multiple ports and on fuel is still new to me.

Now if you regulate the return, do you regulate both the return from the heads and k16 or what?

Dzchey21 · Aug 21, 2013

Yes all returns are common. They all go back thru one single line.

ignore the pressure and volume valves for this conversation. They are both on the high pressure side and they both have nothing to do with the low pressure side.

There is s low issue pump built in to the hpfp but it's a vane pump. That's what the volume control pump does is regulate how much fuel goes into the pressure side of the pump. The pressure control valve just fine tunes the fuel pressure. Most of the work has been done by the volume valve first

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Dzchey21 · Aug 21, 2013

The factory does use a regulator to set fuel pressure to like 2 psi which is plenty imho they jusy want positive fuel flow to the pump.

I think in that schematic its also called an air remover.

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00Powerstroke · Aug 21, 2013

Dzchey21 said:
Yes all returns are common. They all go back thru one single line.

ignore the pressure and volume valves for this conversation. They are both on the high pressure side and they both have nothing to do with the low pressure side.

There is s low issue pump built in to the hpfp but it's a vane pump. That's what the volume control pump does is regulate how much fuel goes into the pressure side of the pump. The pressure control valve just fine tunes the fuel pressure. Most of the work has been done by the volume valve first

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So as far as the returns I could Tee them and run a single return line or run them to a distribution block and run one return line?

Ok, i think i got the majority of that, so lp is not regulated going into the pump but you do want around 10psi regulated correct? So there should be a regulator off the lpfp?

Also i understand return pressure being regulated helps control inlet pressure on the k16 correct? If so then both feed and return lines should be regulated or am I completely off?

09stroker · Aug 21, 2013

It's very simple, all you need is pressure at the HPFP inlet(set with air dog internal regulator or external regulator if using A-1000). What you do with the return line is totally up to you. You can let it return to tank or tie it in to the regulator. That would let it partially circulate back around to the HPFP and partially return to the tank.

00Powerstroke · Aug 21, 2013

09stroker said:
It's very simple, all you need is pressure at the HPFP inlet(set with air dog internal regulator or external regulator if using A-1000). What you do with the return line is totally up to you. You can let it return to tank or tie it in to the regulator. That would let it partially circulate back around to the HPFP and partially return to the tank.

Well thank you for making it simple, albeit this is helpful I want to understand why, not just how. Its how i am with everything.

Is too much pressure to the HPFP a bad thing?

09stroker · Aug 21, 2013

Why what exactly?

00Powerstroke · Aug 21, 2013

09stroker said:
Why what exactly?

why regulating on one side or another is better, if too much psi is bad, so on and so fourth.

Beans71086 · Aug 21, 2013

00Powerstroke said:
Well thank you for making it simple, albeit this is helpful I want to understand why, not just how. Its how i am with everything.

Is too much pressure to the HPFP a bad thing?

I don't know how much pressure the hpfp can take at the inlet side, but considering they set the factory lpfp at 2psi and the a1000 will push 80psi...... you get the idea.

You can either regulate the feed to the hpfp and let the returns flow back to the tank, or regulate the return from the hpfp which will in turn regulate how much the hpfp gets. Either way it needs regulated.

09stroker · Aug 21, 2013

What setup only regulates only the return line????

Beans71086 · Aug 21, 2013

09stroker said:
What setup only regulates only the return line????

http://i1103.photobucket.com/albums/g464/Beans71086/null-72.png

Yeah never mind, I'm confused myself at the moment. I read this in the other thread, now re reading it I'm left with questions.

If I have a pump that produces 80psi and what I'm feeding is only suppose to get 10psi, then I put a regulator of the far side of what I'm feeding that's set to 10psi. Isn't what's between the pump and regulator still seeing the 80psi?

I realize its only going to get so much flow because the regulator is restricting that also, but the flow between the pump and the regulator is still going to be pressurized at 80psi right?

Maybe Dustin can clear this up for us.

09stroker · Aug 21, 2013

No, not on a bypass regulator. On the regulators if you look at them you will see that all the ports are common with each other. Mine for example is a 4 port regulator. That doesn't count the inlet port and the return port. So the (4) -6 outlet ports are always connected to the -10 inlet port whether its at 0 psi or the max. The regulator simply opens the port to the return to bypass some fluid to lower pressure. With that said it would not matter if you ran the -10 hose straight to the HPFP inlet and just tee'd off somewhere inline to the regulator or ran the -10 hose to the regulator then from the reg to the HPFP because either way they are always connected to each other.