You all seem to forgot quite often,that pickup is just one platform with these engines..

Now in a van,fuel bowl is pretty well hidden.
For example,access to the HPOP rear plug requires turbo removal.

513K in odo with stock fuel but i've been thinking of getting rid of the bowl,to clean up the valley and to get straight access to HPOP.

 

Agreed with the guys above. Seems to me the fuel bowl gets most of the air out of the fuel, but FRx gets the last bits. Only 60ish psi but that will keep the bubbles scampering for the exit the FRx provides. And the constant flow out of the head helps keep fuel moving past 6 to fill 8. My truck was quieter with the FRx.

I'd like to see a PERDELS before and after FRx install. That testing is complex tho, many things impact PERDELS. To get a real sense of it you'd need like 10 runs, toss out top and bottom as outliers then average the rest.

 

I would delete the stock filter in a van in a heartbeat.... Injector longevity be damned!!!

If Dante was still alive, Inferno would have included servicing the fuel filter on a 7.3 PSD E-Series.

 

Your right Finlander, I know I do... At least until you or someone like you poses a question or idea to the group so we can shoot holes in it. We always say that every truck is different and every owner is different, so your van is very different from our trucks and should take the best course of action you see fit. Just as you have in the past with your Holset turbo, DIY T4, intake and etc... You my friend, are an exception to most things around here and we like it that way.

I will now retreat to the corner of the discussion where I will watch and learn from a distance.

 

FRx doesn’t really ‘eliminate’ air. It just moves it to another place. (See last paragraph below)

I guess the concept that fuel flowing past #8 is what makes people think it is not ‘starved’. Is this because it can draw fuel from down stream of the injector?

I think what we see in Jack’s testing may be the result of increased turbulence from all of that volume flowing through the messy path through the heads.

That said, the FRx is not a full flow return like a post-head regulated ‘RR’ system.

Has anyone ever measured the volume of the return fuel? Seems like if we can exceed the volume of the OE fuel pump with larger injectors - there would be no fuel to return. Basically, if measuring fuel pressure post filter the way most people do - if we see pressure below the FPR setting, the FPR is ‘closed’ and not returning fuel to the tank.

Also, if the in-tank mods have not been completed - we are just recycling air back to the fuel pump.

My question is - where does this ‘air’ come from in the first place? We’ve established the factory filter assembly does an excellent job of removing air that could be the result of turbulence between the pump and the filter (or the RARE situation where the pre-pump quick connect fittings leak).

 

I shall now throw a wrench into this discussion, Have any of you considered a pump controller so you can run a returnless system?

 

This is kinda what I am doing. The return to tank is at the outlet of the airdog2 pump assembly, then just a single -8an hose going up to the cncfab block and 4line feed

 

Ah but that still has a regulator in the system. I’m talking about controlling the pump to provide fuel pressure to set point. That means a single fuel line from tank to engine.
https://www.underhoodservice.com/poi...ction-systems/

 

I don't see any gain with that, does the same job, but puts everything in tank, so any service is a pia. I will be running a sump for the feed/return, return line is only gonna be like 4' long. No need to ever drop the tank again (save for a 67 gallon titan install someday) Also should have enough air free fuel flow to feed just about any injector. Filter changes will be easy as well

 

You don’t necessarily have to have the pump inside the fuel tank. The idea is to control the duty cycle of the pump to match what the engine is demanding for fuel. It’s supposed to increase pump life by not overworking it at low engine power levels.

 

The airdog, etc are ‘internally regulated’ and just return fuel from the FPR to the suction side of the pump.

So at idle the pump still moves 95gph or whatever even though the demand is only 1gph.

I got aggravated with ‘click to read more’ in FTN’s link. But, the PWM controllers were gaining popularity back when the Aeromotive 1000 was a popular pump upgrade.

This could be a good alternative. Reducing the amount of fuel flushing around the system should reduce turbulence that causes ‘air’.

 

FTN could be on to a good idea.
WIth the integrated return on the g&r sump that alone is supposed to help reduce bubbles compared to the way airdogs return works.

Also, I was interested to see kc turbos new vid, where a guy made 568hp or so and like 1200torque
With 238/80 and the airdog 2 and cncfab 4 line feed. Guess I wont have any fuel flow issues :-)

 

SSJ poses a very good question...Where is this air coming from? Turbulence does not create air. It would only cause "air" suspended in the fuel to separate. At some point, air would have to be introduced to the system from somewhere. There is the possibility that sloshing in the tank could allow some air to be ingested by the fuel intake, but that would be minimum unless running very low on fuel. I can see where there would be temporary air introduction when doing things like changing the fuel filter, or otherwise opening the fuel system.
Let's look at another closed system...how about a hydraulic system on say a dump truck? It has a reservoir, high pressure pump, and it circulates fluid and returns fluid to the reservoir. Even when I operated a dump truck that we took a sand spreader on and off of, we never really worried about air in the system...even when connecting and disconnecting hoses regularly. Now, there is not the constant returning of fluid to the reservoir like a fuel tank would have, but during snow and ice events we would leave the PTO engaged in these trucks and drive up and down the highway, so that way we did not have to pull over and come to a complete stop to engage PTO every time we needed to use the spreader...so in that case, there was a decent quantity of fluid circulating constantly. Once again though, never saw any negative effects that could be from aeration of the oil. I would think that hydraulic oil would take longer to clear air also, since it is thicker. Maybe I am completely off the ranch with this comparison, but it seems similar enough.
In the end, the air does have to come from somewhere. Turbulence does not create this "air", it could just make it reveal itself...but it has to be there to begin with.
Maybe a closer comparison would be a gasoline EFI engine...the fuel pressures are around the same, and the system operation is similar..."high" pressure pump pressurizes fuel system, pushes fuel under pressure through the fuel rail, injectors fill, discharge, excess fuel volume and pressure are pushed back to the tank with the use of a pressure regulator. You don't see air introduction issues with these systems...

 

This man gets the point I am trying to make.

 

Even a blind squirrel finds a nut every once in awhile.

I smell what you’re stepping in there and I love the addition to our discussion.