I was ordering parts this morning for another project and I stumbled upon an inline fuel pump and had an idea. Figured I'd run it by the folks here before I wasted my time on it. What I want is, I want to raise fuel pressure at the rail while in boost, without running a return line to the tank. I've maxed the injectors and I've been dreading taking the fuel pump out and hacking up the housing and running lots and lots of braided steel line to convert it to a return type system. So I spent most of the day going over this plan to support my laziness, and I can't find a flaw with it - but maybe someone here can. Here goes.

1 walbro inline fuel pump (60gph @ 40psi rating)
1 Adjustable FPR (any will work for this application)
4 ft fuel injection hose

I'm planning to connect a walbro inline fuel pump into the fuel line in the engine bay somewhere, which will in essence turn the factory pump into somewhat of a scavenger and relieve the duty of pressurizing the rail (fuel pumps flow more fuel at lower pressure anyway). Ok so the 2nd part of this, I want to put a rising rate fuel pressure regulator on the rail, and run the return back to the inlet of the secondary fuel pump (rather than all the way back to the tank). In essence, this should keep pressure in the rail higher than pressure in the line between the pumps, and the factory FPR in the tank should ensure no higher than factory pressure between the pumps. I intend to install a pressure gauge inline between the two pumps to ensure I don't draw a vacuum, but I doubt this will be an issue at 17psi of boost pressure.

Thoughts? Am I crazy, or will this actually work?

hmm, pressure is a resistance to flow, with out having enough flow in the first place I donm't see how this would work. Also you would need check valves to make sure you keep the pressure where you want it.

This set up would not work in hydraulics so I doubt it would in a fuel system. Just buy a pump that flows more so that the other inline pump has enough flow going into it to work. You need one pump to flow lots of gas at low pressure, and one pump to flow at high pressure. a two stage pump.

Look up the Aeromotive Digital FMU. If you replicate that system with check valves you can boost pressure in the line without running a return. This is what I used at first. Although, I have to recommend just upgrading your pump and tuning the car well

Cool. I'll let you guys know what I decide. If I have to, I'll make a return line and upgrade the pump. But I'd rather not go that route if I don't have to. Anyone know what the factory fuel pressure is for our cars?

I believe its 44psi

No wonder I'm hitting over 90% IDC.

Huh?

Whats your mods, psi level, size turbo etc... please

GT2871R @ 17psi, Built 2ZZ, Hydra EMS, 680ccs

A number of others I'd rather not disclose. Most related to the gear box.

I'm aiming for A/Fs between 11.5 and 12:1 on pump, spraying lots of meth.

At that level, I would honestly do it right and just run a return line. It isnt very complicated and will guarantee smooth safe performance. Just my .02

I know. I just hate working back there. Everything has razor sharp teeth of death, and once you cut into the fuel pump housing, there's no going back. I'll think on it. I'm looking at a progressive multi-port meth system as well. Racing methanol is actually cheaper than gasoline right now. lol

You MAY need to bump up slightly with your injectors as well. Get the delivery straightened out first, then check the IDC's again.

whoa 680cc injectors and you think he needs bigger ones? that's a crazy amount of fuel.

Hi, I havent browsed the boards in awhile, but this thread caught my eye.
I have a turboed 03 vibe with the 1zz running about 11psi ON STOCK INJECTORS!

MY fuel set up is in the direction you are headed. I have an inline fuel pump up by the fuel rail. The pump is referenced to a hobbs pressre switch than only comes on during boost. There is a bypass fuel line around this pump with a check valve in it for when you go into boost. I have a RR regualtor that needs a return line , but i dont have one . My rising rate regulator, is like the vortech ones set at like a 12:1 ratio. At turbo 10psi, do the math on how much pressure runs in my fuel rail when I boost I have been running like this since 2003. In stead of returning the fuel back to the tank, it is returned to before the secondary pump, a check valve is involved. It works.
With your set up, and bigger injectors, you could set it up so that you dont turn on the pump and raise the FP until you got to a certain air/turbo psi. Everybody thinks this is too much fp in the rail, but they forget that it does not run this high all the time, but only in spurts. I do not have failed injectors. I have run at the track up to 14 psi , running pig rich 10:1 or 11:1 AF ratio on stock injectors.....it works...I dont even retard my timing. Everyone told me it would not work, but everyone is a magazine tuner.
Keep going , just watch everything , it will work.