Late Model Toyota Non Return Fuel Rails and Their Associated Pumps and Plumbing

[MR22ZZ]

I don't see what's so difficult about the system I suggested? It is exactly what is done currently anyway on a standard surge tank setup, lift pump to surge tank, 2nd fuel pump to rail. The only difference is that there is a FPR before the rail and a return line there instead. As long as the pump keeps the same pressure to the rail as the standard 2ZZ in tank lift pump, that's all that matters. Unless you are going to go nuts on the engine there after, that's all you require.

As for your question, that's exactly what I'm suggesting isn't it?

[wagonist]

If you can get hold of a the standard 2ZZ in tank setup (fuel pump, filter FPR), then I suppose you could install the lot into your surge tank, use any kind of pump to fill the surge tank (existing MR2 one?) & run the FPR return line either back into the surge tank or the original fuel tank.
That's fairly simply to do as you'd just make the surge tank to fit around those components instead of having them outside the surge tank like most installations.

Not sure how large this swirl pot will be.

For Clint, it could be the same.

[wagonist]

I don't see what's so difficult about the system I suggested? It is exactly what is done currently anyway on a standard surge tank setup, lift pump to surge tank, 2nd fuel pump to rail. The only difference is that there is a FPR before the rail and a return line there instead. As long as the pump keeps the same pressure to the rail as the standard 2ZZ in tank lift pump, that's all that matters. Unless you are going to go nuts on the engine there after, that's all you require.

As for your question, that's exactly what I'm suggesting isn't it?

The problem I was seeing is that the newer non return stuff is all designed to inside the tank, whereas every aftermarket external surge tank has external filters, pumps, etc.
This keeps the physical size of the surge tank down & the return line is "aimed" so that the fuel within the surge tank doesn't get aerated (thus causing issues with pickup).
If everything is mounted within the surge tank, it'd need to be a lot bigger, also designed to be accessible (& sealed) to change pump, etc if necessary).

How is FPR on returnless system controlled is the big question.
Is it fixed & then the ECU varies the pump speed (I've heard this somewhere),
or is the FPR given some kind of input to change the volume of fuel going to the engine,
or some combination?

[MR22ZZ]

If you can get hold of a the standard 2ZZ in tank setup (fuel pump, filter FPR), then I suppose you could install the lot into your surge tank, use any kind of pump to fill the surge tank (existing MR2 one?) & run the FPR return line either back into the surge tank or the original fuel tank.
That's fairly simply to do as you'd just make the surge tank to fit around those components instead of having them outside the surge tank like most installations.

Not sure how large this swirl pot will be.

For Clint, it could be the same.

That was one of the ideas I had, would definitely be the most 'simple' way to do it, other than the whole custom surge tank to fit around the 2ZZ intank pump business.

[horse]

Clint, I take it you're asking for Loz' car? if so then the fwd beams run return, the altezza returnless. From what i can recall Glen says you just swap one to the other and there you have your return system. if you need pics/part no's etc of fwd one let me know.

ok just realised that you did want to run std ecu. have you thought about getting an altezza fuelpump and run that? or are there other constraints?

some info here Clint.
http://www.mr2.com/forums/beams/Toyo...a-project.html

[CLG]

The only constraints to sourcing and running an Altezza fuel pump for Lauren's RA28 are:

1: Actually sourcing it at a respectable price for a new or secondhand unit.
2: Sourcing the required filter to suit the pump.
3: Ensuring it can be installed into the RA28 fuelk tank without major modification (I see this as the biggest hurdle)
4: Determining the requirements of the standard RS200 ECU and injectors if it all turns to shit and we decide to utilise a return fuel system - matching pressures, and flow wise.


The Altezza injector part number is 23250-74220, while the FWD BEAMS (ST202 Celica) injectors are 23209-74160, and 23209-74190 - can anyone give me flow rates, and impedence of these three injectors? The rail on the Altezza motor would easily be modified to run a return, not only doe it have the centre feed banjo fitting, but also two tapped bungs at each end of the fuel rail.

[wagonist]

4: Determining the requirements of the standard RS200 ECU and injectors if it all turns to shit and we decide to utilise a return fuel system - matching pressures, and flow wise.

I know this is a bit hit & miss, but couldn't you use an adjustable FPR & then get it tuned (along with checking fuel pressure) to work this out?

The rail on the Altezza motor would easily be modified to run a return, not only doe it have the centre feed banjo fitting, but also two tapped bungs at each end of the fuel rail.

Considering this, I'd just be going for the simple tried method of using a returning system. I'm guessing this rail is also fitted to other engines as well.
FYI, my fuel rail is fed from the bellhousing end with the FPR at the other.

[oldcorollas]

suprised no-one posted this yet....

http://www.autoshop101.com/forms/h42.pdf

reason for returnless is to decrease evaporative emissions from the fuel tank.

toyota has constant 44-50psi (but i thought someone had said 60psi before?)
pump is typically turbine type, and has enough capacity for stock engine plus a bit more (dunno how much)

[thechuckster]

so if you kept the factory ECU, went to a return system and used a FPR that regulated pressure to MAP, you'd stuff the motor as the fuel maps would be based on having a constant rail pressure rather than one relative to manifold vacuum/pressure.

[wagonist]

Maybe the FPR doesn't have to have a MAP reference, I mentioned adjustable so it could adjusted to the required rail pressure to match the mapping. Then it would be fixed.
But there must be a way then that the fuel pressure is increased for higher rpms?
Pump speed is increased? Can normal EFI pumps have their speeds varied?

[oldcorollas]

But there must be a way then that the fuel pressure is increased for higher rpms?
Pump speed is increased? Can normal EFI pumps have their speeds varied?

why?

the fuel pressure is STATIC.. meaning it doesn't change.(that doesn't mean the fuel pump RPM doesn't change when controlled by the ECU, but the fuel in the rail is the same pressure)

why would you need to increase pressure with RPM?

[wagonist]

Been a long day For some reason I was thinking the injectors kept a constant duty cycle & the fuel pressure increased

Though it does beg the question as to why there is a MAP line to the FPR (for a returning system)?

[oldcorollas]

Been a long day For some reason I was thinking the injectors kept a constant duty cycle & the fuel pressure increased

Though it does beg the question as to why there is a MAP line to the FPR (for a returning system)?

it must have been a long week

do you understand how EFI systems work at all?


lemme make it simple for you.
injectors always vary their pulse width to change the amount of fuel injected.

returnless systems have constant pressure, which is higher than return systems, due to potential issues of fuel vaporising in the rails due to engine bay heat. to make it simple, the fuel pressure is constant.

return systems have a fixed fuel pressure differential across the injectors.
for example. a diferential of 40psi means that the real fuel pressure minus the manifold pressure, is always 40psi. this makes it easier to work out fueling, and has the benefit of letting the pump work less for 95% of the time when you are not on throttle.
to maintain the pressure differential, the regulator needs to be MAP referenced.

[wagonist]

I did own a turbo diesel for 7 years. and i learnt everythings I knows from the internets. You know that never lies

Your explanation of the returnless system did answer a few q's though.

[oldcorollas]

diesel is different

common rail have injectors that meter, but in other systems the injectors are just hoses, and the metering is done at the metering/distribution block thingy..