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

[CLG]

I have a couple of conversions to do which have fuel rails without fuel return capabilities (2JZGE VVTi and 3SGE BEAMS). As I've never played with this style of fuel feed before I have a few cusory questions?



1: Do the fuel pumps used in these non return systems differ from older model EFI pumps that have a fuel return (to tank) feature? If so, how?

2: How do these late model non return rail setups regulate flow and pressure, and where is it regulated - at the pump, rail, or elsewhere?

3: Is it easier to add a fuel return feature to these rails when retrofitting these engines into older cars?

4: What are the requirements when selecting a fuel system that has no fuel return capabilities, in retrofitted applications?

5: What are the voltage requirements of this style of fuel pump, I would assume they lower voltage and therefore flow and pressure at idle?

6: What are the operating fuel rail pressures for this style of setup at idle, and open throttle situations?

7: Has anyone got a non return system currently fitted and operational? - Is it reliable, do your pumps run "hot", did you stumble upon any rays of sunlight when developing your system, and are there any pitfalls to be wary of?



At this stage, the only plans I have as definite, are to run new 5/16 fuel lines from the pump to the fuel filter, who can help me answer the above questions, so I can best determine my needs? Both the 2JZ and the 3SG will be run by their respective standard Toyota ECU's, no attmepts to increase performance will be made during this round of installaion, and orientation.

[Vios-GT_07]

1. nope.. i have a returnless system in my car and i've swapped a walbro GSS342 (255 lph) fuel pump... most toyota returnless system i know of have the fuel pump as part of the filter assembly.. so changing the fuel filter involves removing fuel pump as well. i know of people swapping over different fuel pumps, from S15 silvia to mitsubishi FTOs etc etc and it works fine..

2. fuel pressure regulator is at the bottom of the fuel filter assembly..

3. the returnless system is designed such that fuel is not returned to the system,.. it has merit, but can be endlessly debated i.e. hot fuel coming back, fuel getting lost as vapour, more parts needed for return system, etc etc... turning it to a return system involves a different fuel rail (which has a return line) a tank that has a return line, fitting return lines to it, fitting a fuel pressure regulator, etc etc... it can be done, but in my opinion the returnless system is efficient and i wouldn't bother messing with it...

4. there are no requirements... i've seen people fit the 2AZ engine (which has a returnless setup) to a car that has a return ... they had to modify the car a bit to fit the 2AZ's fuel tank, as it was much easier to use the fuel tank for that engine, for the correct fuel pressure regulator, fuel filter and fuel pump..

5. voltage wise, it's the same as a conventional fuel pump as far as i'm aware, but i might be wrong.. that said i've seen people run a relay to power the factory pump, as well as a relay to run a walbro.. i just ran the walbro off the factory wiring, had higher pressure at the engine, was easier than messing around with the fuel pressure regulator..

6. unfortunately my fuel pressure would be different than yours.. as i have a smaller engine.. i can't remember what the pressure was at idle and under full throttle but the fuel pressure gauge i had read 2.8 at idle and 4.0 on full throttle.. if it makes sense?

7. with the factory fuel pump it only runs hot when i drive it to 1 liter left in the tank.. like most other normal in-tank fuel pumps? with the walbro if it gets to anything less than 5 liters left in the tank it will whine like a bitch..

hope that helps, otherwise i have some general technical info regarding returnless systems for some toyota cars, and it identifies the components of the returnless fuel system.. it's the same for all FWDs but i think it's very similar for RWD cars as well..

[Cuts]

We've just ran into issues with supercharging a zzt231 celica, with 510 squirters and an uprated pump (cant remember brand or flow but was plenty big enough for the application).

Even with the bigger injectors we were running out of duty cycle as soon as it hit lift, and if we were to fit bigger ones so as to provide enough flow at high rpm it would be too ruch at idle, the 510s are at .6 ds at idle, and the mininum you can go on the pfc is .5.

So an AEM returning system has been bought, full legnth braided line, all fittings, reg, guage etc. Was pretty good price i thought at $350 us i think.


Same in the 231 pump filter and reg are all in the tank. I assume that it only ups the fuel pressure by speeding up the pump over a certian number of revs.

[CLG]

1: So is the Walbro actually designed to work with a non return system, and what happens to the pump when the fuel rail is presurised? My pump and filter options are open at the moment, but I will need to consider the MS57 Crown ute fuel tank (for the 2JZ), and the RA28 fuel tank (for the 3SG) - and the modifications needed to run a late model pump. If building the fuel system allows for an easier alternative, I'll more than likely head that way (ie external pump, and seperate filter in the engine bay), as I have no intention on fitting a "returnless" fuel tank.

6: What unit of measurement - Bar?

[Vios-GT_07]

1. the walbro is a universal pump.. the walbro GSS342 is designed to work as an internal fuel pump.. and as far as i know there is no difference between return and returnless fuel pumps...

when the fuel rail is pressurised, the fuel pump keeps running as long as the engine is still running.. excess pressure / fuel is regulated by the fuel pressure regulator, which is part of the fuel filter + fuel pump assembly

think of it this way.. in a return system, the fuel pressure regulator is fitted on the return line of the fuel rail... but in a returnless system the fuel pressure regulator is in the tank..

pics as follows

[Vios-GT_07]

anyway
6. yea i think it was in bar... 90% sure it's in bar..

[thechuckster]

are you sure?

1bar = 14.7psi and static pressure in your garden variety return-system is 38psi (engine off, pump on).

Does a return-less system really run at 4-6 bar? (58 - 88psi)? that would be well out of the efficiency range of a fuel pump designed for a return system.

[MR22ZZ]

There's a small amount of information in here from when I was thinking of the same issues.
http://www.toymods.net/forums/showth...ght=returnless

What I'm hoping to do is to run the current return pump as a lifter to a surge tank and then run a fuel pressure reg with return line between a second pump from the surge tank and the rail. Basically like the 1st pic that Vios posted but the pump and reg would be external of the tank.

Also taken from this thread for a 2GR-FE conversion into an SW20 chassis... http://www.toymods.net/forums/showth...ght=returnless

11) Fuel system:
- You’ll need a high flow fuel pump. I’m using the supra pump I had already installed for the 3sgte and it keeps up without a problem.
- I made a small bracket to attach the regulator to the forward head, the regulator has a return on it and outputs to the stock returnless fuel system. I retained the stock fuel filter in the stock location.
- To keep things clean and functional i used the stock MR2's map sensor filter on the pressure regulator's atmospheric reference.

[wagonist]

I'd be trying to just make it simple & make a returning type fuel system.
I think (can't remember where I saw it) there was something about the fuel pump having varying speeds or something so that excess fuel doesn't end up in the rail.

All the conversions I've seen (mostly 1MZ) install a 3VZ fuel rail & use single voltage to the pump.
Alternative is to modify the end of the rail to accept a fitting, and if that isn't thick enough, cut the end off & weld on a thicker piece to drill & tap.
For all the headache of trying to fit the returnless system in, IMHO it's just easier to make a returning type system.

[oldcorollas]

are you sure?

1bar = 14.7psi and static pressure in your garden variety return-system is 38psi (engine off, pump on).

Does a return-less system really run at 4-6 bar? (58 - 88psi)? that would be well out of the efficiency range of a fuel pump designed for a return system.

i've heard numbers of 60psi being bandied about for some returnless systems. they were NA motors tho, so no need to go above that.
and something abotu PWM control of the pumps....
Mos would know

[Vios-GT_07]

^^

so... like this? (excuse my crappy diagram)


or from gouky, from what i gather about his setup he runs it like this..



i always had concerns about fuel pressure, especially when it was a fad to install the walbro for the returnless system.. but yea after seeing how it worked i found it was no different than a return system... i'm still having doubts about fuel pressure but it looked like the same pressures as a return system..

chuckster - i don't see anything more than 4 bar, and it sits around 2.5 to 2.8 at idle.. i remember the moment i turn on the key it would prime to 3 before settling down to 2.5 or so, then after starting it would sit around 2.8..

[MR22ZZ]

I'd be trying to just make it simple & make a returning type fuel system.
I think (can't remember where I saw it) there was something about the fuel pump having varying speeds or something so that excess fuel doesn't end up in the rail.

All the conversions I've seen (mostly 1MZ) install a 3VZ fuel rail & use single voltage to the pump.
Alternative is to modify the end of the rail to accept a fitting, and if that isn't thick enough, cut the end off & weld on a thicker piece to drill & tap.
For all the headache of trying to fit the returnless system in, IMHO it's just easier to make a returning type system.

Interesting choice of words there Steve.

Simple option, it is not.

Have a talk to Xoom.

[wagonist]

What's not simple about modifying a fuel rail to accept an aftermarket fuel pressure regulator & then connecting it to your existing fuel return line?
No tank mods necessary, no fuel line mods necessary (except that you want to install a surge tank).
That system is tried & trusted. Aftermarket people are still trying to figure out properly this new way.

A question though:
could the in tank fuel pump be kept constant, and a FPR that would normally be situated on the end of the fuel rail be fitting into the tank position instead?
I'm guessing this would need a reference vacuum feed from the engine though.

[CLG]

For ease of simplicity, I would prefer an external mount fuel pump, this would save me having to modify the fuel tank.

[wagonist]

^^

so... like this? (excuse my crappy diagram)

Except the high pressure filter would need to be relocated to between the surge tank & FPR.
Clint, if you're using the existing tank with an external pump into the surge tank, then there will be a need for a filter between the fuel tank & pump. But I'm sure you've been doing this long enough to know this.