Unregulated or Regulated return

[Morgan@Midwest Diesel & Auto]

There will be a new kit on the market very soon that addresses all these options. But honestly there is absolutely no reason to regulate pressure on the return side. Not trying to make enemies here, just stating the truth, not dancing around it.

 

[Stroked777]

Ok I understand. It was just one of those "thinking about everything before bed" ideas LOL

 

[CT9AIX]

Have had the feed regulated, return unregulated for 30k + miles with no issues. As Morgan said no reason to regulate the return and it makes like easier anyway for install

 

[V-Ref]

This is not a 7.3 or 6.0 that feeds injectors through the heads guys. They are a freaking common rail. No regulation is needed on the return, the same for and cp3-4 pumps engines either. You give the pumps 8-10 psi so they have a steady supply of fuel and the rest is history. Nothing to argue about here.

http://powerstrokearmy.com/photopost/data/548/medium/Diag.jpg

Morgan...and others...teach me here.

On a regulated fuel system (regulated supply or regulated return)...pressure is only regulated between the source of pressure (the pump) and the regulated restriction (regulator). I'm assuming you set the pressure on a Airdog/Fuelabs/etc systems (never had one, please excuse if I'm not understanding how these are setup exactly) while the truck is at idle.

Without a regulated return how do you guarantee what the HPFP supply side fuel pressure is during high fuel demand operations? I'm not seeing how a regulator between the electric fuel pump (Airdog/Fuelab/etc) and the HPFP would compensate and ensure the HPFP ALWAYS sees 8-10 psi (or whatever the desired pressure).

I understand fuel temp concerns....but as long as the return pressure isn't cranked beyond the spec you want the HPFP to be supplied with in the first place....I'm not seeing how this creates a situation with less fuel being moved by the HPFP.

Have you monitored HPFP supply/return fuel temps and compared them on a regulated supply vs a regulated return type systems? If so, any data you have to share would be great.

Thanks in advance for the insight/perspective.

 

[HOOV3R]

http://powerstrokearmy.com/photopost/data/548/medium/Diag.jpg

Morgan...and others...teach me here.

On a regulated fuel system (regulated supply or regulated return)...pressure is only regulated between the source of pressure (the pump) and the regulated restriction (regulator). I'm assuming you set the pressure on a Airdog/Fuelabs/etc systems (never had one, please excuse if I'm not understanding how these are setup exactly) while the truck is at idle.

Without a regulated return how do you guarantee what the HPFP supply side fuel pressure is during high fuel demand operations? I'm not seeing how a regulator between the electric fuel pump (Airdog/Fuelab/etc) and the HPFP would compensate and ensure the HPFP ALWAYS sees 8-10 psi (or whatever the desired pressure).

I understand fuel temp concerns....but as long as the return pressure isn't cranked beyond the spec you want the HPFP to be supplied with in the first place....I'm not seeing how this creates a situation with less fuel being moved by the HPFP.

Have you monitored HPFP supply/return fuel temps and compared them on a regulated supply vs a regulated return type systems? If so, any data you have to share would be great.

Thanks in advance for the insight/perspective.

The Hpfp has an internal transfer pump, which then supply's the actual high pressure pump. The high pressure pump controls its pressure by regulating its return. The only part that isn't regulated is the lubrication fuel from the transfer pump.

 

[V-Ref]

The Hpfp has an internal transfer pump, which then supply's the actual high pressure pump. The high pressure pump controls its pressure by regulating its return. The only part that isn't regulated is the lubrication fuel from the transfer pump.

I see....hmmm....so a regulator between the hpfp and tank could interfere with the hpfp ability to regulate rail pressure. ..am I understanding that right?

 

[Morgan@Midwest Diesel & Auto]

The supply pressure from the lift pump is the same all the way to the hpfp, we regulate that pressure and dump excess back to tank. After it passes through the hpfp it goes into a return line back to tank with zero pressure held on it by a regulator, hence the "unregulated" return line pressure.

 

[V-Ref]

Does anyone have data on fuel pressure differences between an electric fuel pump like an airdog/fuel ab and the hpfp from low to high fuel demand operations?

 

[HOOV3R]

I see....hmmm....so a regulator between the hpfp and tank could interfere with the hpfp ability to regulate rail pressure. ..am I understanding that right?

Not really.

 

[V-Ref]

The supply pressure from the lift pump is the same all the way to the hpfp

I'm not understanding this statement.

My question:
If the lift pump is "set" to provide the hpfp 8-10 psi of pressure at say an idle/low fuel demand operations, how is 8-10 psi provided during high rpm/high fuel demand operations?

I've looked over the diagrams posted (thank you)....and still not seeing it.

Thanks in advance for replies in explaining this.

 

[BOSS450]

The regulator will simply keep pressure to the 8psi needed. Less fuel will bypass and return to the tank.

 

[B585Ford]

I'm not understanding this statement.

My question:
If the lift pump is "set" to provide the hpfp 8-10 psi of pressure at say an idle/low fuel demand operations, how is 8-10 psi provided during high rpm/high fuel demand operations?

I've looked over the diagrams posted (thank you)....and still not seeing it.

Thanks in advance for replies in explaining this.

The LPFP is pushing way more fuel than HPFP could use. Fuel Lab produces 200 GPH and our injectors maxed out can only push out ~80 GPH so pressure to the HPFP remains constant even with an unregulated return cause LPFP flows so much more fuel.