Why won't this work? Fuel system plumbing on the cheap...

[IowaOffRoad]

I have all these pieces at hand, trying to build something durable enough to last with what I've got. Fuel source (diesel) fed to engine. Need inlet to engine fuel pressure ~19si. Pump produces 60psi (Bosch external inline) and doesn't like to run restricted without getting hot and dying. Fuel pressure regulator is a Holley non-return 4-9.5psi regulator. Drawing above. Think connecting the inlet and return with the regulator will work, at least good enough to maintain 9psi in a fairly stable fashion? Should I just go buy the right parts (of course I should)?
Forget the platform or what its running in, I've never seen a setup like this in the wild but I cannot convince myself it won't work. Seems to me the HP pump on the engine should draw what it needs and the regulator should bleed off what it don't.
Gonna try it anyway, but I thought the debate might teach us all something.

 

[Clb]

Why a non bypass reg.?
I feel like it would be fine if it was a bypass type.
The full flow reg may cause low delivery pressure issues, when it opens.
Thats how the idi gurus seem to make them up.

 

[IowaOffRoad]

Theory is the engine takes what it wants and fuel only bypasses when it’s over 9.
Path of least resistance.
Why? I have the parts and I’m bored. Why not?
It also fits better in the current fuel infrastructure and non-bypass regs are cheaper, if anyone would care to replicate it.

 

[AKnate]

Why not just use a 20psi clicky clacky pump?

What engine?

 

[YotaAtieToo]

To me it seems like the engine would get too much fuel.

But on the other hand I can see how the regulator shouldn't let it go over 9?

 

[IowaOffRoad]

Why not just use a 20psi clicky clacky pump?

What engine?

Common rail 6 in a test cell. Can’t give any more details about that. Prolly gonna end up with a proper regulator but it’s the only regulator we have on hand ATM that’s compatible with diesel

 

[Tiha]

Can the engine handle any back pressure.

If the return isn't big enough that is the only problem I can see.

 

[Bebop]

Run the 2 returns separately.

 

[arse_sidewards]

It's in a fucking fuel cell. Put a 55gal drum on the roof and run a ball valve.

25-30 ft should get you the 9psi you need.

 

[IowaOffRoad]

It's in a fucking fuel cell. Put a 55gal drum on the roof and run a ball valve.

25-30 ft should get you the 9psi you need.

Have to measure the fuel consumption or we would use the day tank (and I’m aware that we could weigh the barrel, we’ve done it before).
Yes, there are many ways to accomplish this, but there are constraints as to how I have to run this. The actual limitations are -50kpa to +200kpa. I’m targeting 9 because it’s at the top of this regulator’s capacity and it’s the only regulator we currently have available that is compatible with diesel. I’m hoping to be able to turn it down to 4 (the lower end of this regulator) while running under load.
I put this out there where I did as I can see the benefit to running a high pressure pump with a regulator setup like this in the real world because both components are cheap and could possibly work like a poor man’s FASS or Airdog. It seems to me that the “expensive” part of this system (pump) should run a long time with the only real concern being the $40 Holley regulator that’s available most places easily.
Relax arse, this isn’t an exercise in what other options are out there, but whether this particular option will work.
We will know if it will support the fuel demands of 700hp soon enough.

ETA before arse busts my balls:
The reason I wanted to try this is our go-to pump around here, gas or diesel is a Bosch high pressure pump (60 something PSI) that moves a ton of fuel, coupled with a typical bypass regulator, either a 60-30psi range or a 10-30psi range. With this setup, if targeting low pressures or with low fuel demands we seem to either overheat the pump and wear the diaphram out on the regulator frequently. In my mind this setup should reduce the load on the pump and keep the regulator "open" more often (reducing it's 'cycle' rate) even under transitive conditions. My comment about being a 'poor man's FASS' is in regard to being able to move a ton of fuel, use the existing lines, and not having to poke a hole in your filler neck. It may fail miserably, but if it works you the public should be able to put the same setup together for about $80 and be able to service both the pump and regulator anywhere in the states if either fails. I can get the Bosch PN if you'd like, but its my recollection that they move about 250gph free-flowing (this is what we've tested them at, I think it overperforms the box spec by a bit).

 

[SHARPMACHINE]

Seems legit. To test it just install a pressure gage at the engine.

 

[mobil1syn]

only thing that concerns me is if you will be able to get the volume needed to support the hp if your dumping that much fuel to meet the psi number

 

[Clb]

Only real issue then is...
Will it bypass pressure to the pump down to 5 psi???
+1 on gauge @pump

I'm not sure how a 5-9 psi regulator works in this situation.

 

[ParadisePWoffrd]

only thing that concerns me is if you will be able to get the volume needed to support the hp if your dumping that much fuel to meet the psi number

I think you could "tune" that some by adjusting the size of the return line.

If I am thinking of this correctly, the only way for it to work, and keep the pressure at the engine low enough, will be for the regulator to be dumping to correct amount of volume, to drop the pressure from 60 psi to 19. But that likely wont work if the engine demands more fuel, since the regulator will be dumping the same amount all of the time.

 

[IowaOffRoad]

I think you could "tune" that some by adjusting the size of the return line.

If I am thinking of this correctly, the only way for it to work, and keep the pressure at the engine low enough, will be for the regulator to be dumping to correct amount of volume, to drop the pressure from 60 psi to 19. But that likely wont work if the engine demands more fuel, since the regulator will be dumping the same amount all of the time.

In theory fluid or gas should follow the path of least resistance. This is only needed due to the nature of the test and the necessity for the fuel source and measurement device to be 30' from the engine with 6' of lift. The engine has a driven pump that, in it's intended application, would be sufficient to suck fuel from the fuel source (distance less than 8', lift less than 2'. When the variable displacement pump is at low rate, most of the fuel should be bypassed. When the variable displacement pump is at high rate most of the fuel will be drawn into the engine with very little running past the regulator. That's the theory anyway...

 

[mobil1syn]

i will add while im sure there are moments of extended misery, your job sounds entertaining.

 

[IowaOffRoad]

i will add while im sure there are moments of extended misery, your job sounds entertaining.

Can confirm both things you said, wish I could discuss more details

ETA: I've always said that if the job was non-stop fun I would have to pay for it like a theme park. I'm not getting paid what I do for the fun stuff, its for the misery in between

 

[Kreep]

The way I read your diagram the regulator is going to try to maintain 9 psi in the return line. Supply line pressure will be anybody’s guess but will drop as fuel consumption goes up.

I’m running the same layout but with the regulator after the tee in the supply line and a restrictor where you have the regulator on my Samurai. Reason being it has motorcycle carbs that want less than 1 psi. Works like crap.

Let us know how your experiment goes!

 

[IowaOffRoad]

The way I read your diagram the regulator is going to try to maintain 9 psi in the return line. Supply line pressure will be anybody’s guess but will drop as fuel consumption goes up.

I’m running the same layout but with the regulator after the tee in the supply line and a restrictor where you have the regulator on my Samurai. Reason being it has motorcycle carbs that want less than 1 psi. Works like crap.

Let us know how your experiment goes!

Forgot to include the .5psi check valve upstream from the tee

 

[Bowe]

The way I read your diagram the regulator is going to try to maintain 9 psi in the return line. Supply line pressure will be anybody’s guess but will drop as fuel consumption goes up.

I’m running the same layout but with the regulator after the tee in the supply line and a restrictor where you have the regulator on my Samurai. Reason being it has motorcycle carbs that want less than 1 psi. Works like crap.

Let us know how your experiment goes!

I’m using a wix 33040 filter with built in return port and a regulator right before carb set to ~1-2psi. Seems to work fine sending any excess fuel down the return. I’m only feeding one cv40 on a 660cc engine fwiw.

 

[IowaOffRoad]

I’m using a wix 33040 filter with built in return port and a regulator right before carb set to ~1-2psi. Seems to work fine sending any excess fuel down the return. I’m only feeding one cv40 on a 660cc engine fwiw.

Another option is the 33054 (used mid 70s-80s on carb Dodge V8s). I've used filters like this to reduce the pressure on larger lawn mower engines when the crankcase pressure-driven fuel pump dies and replacing it with a 12v low pressure fuel pump.