Fuel line setup question

[Jann]

Dear all,

first off, I'd like to say hi, I'm new here. I come from Poland and I work on my first carb to EFI conversion. The engine is a 3-cylinder two stroke, AFAIK there is no other setup like that already built. The fact it's a 2t will add some problems concerning the engine control and tuning, but it's not the topic now.

In my project, I want to use a fuel rail from triumph 675 since it comes with ITBs that would fit very well concerning the package, pipe sizing and injectors flow. The problem is, 675s have a returnless fuel supply. I imagine the configuration as it's shown in the attached fig.: fuel supply from the pump, then a T-pipe separating the flow towards the rail and the pressure regulator connected to the tank with a return line.

design.png

I know that it'd be better to make a custom fuel rail with fuel return on the other side, but at the first iteration of the project I'd like to minimize the number of manufactured parts. I was looking for answers in the forum, but I found relatively few topics on similar configurations. Therefore:

1. Does any of you have experience with such a returnless fuel line applied in a return-type configuration? Is it gonna work fine? Any drawbacks found? Any tuning issues? Pressure stability?
2. I thought of keeping the distance between the fpr and the Tee small, a few cms. According to your experience - does this distance matter? Would it be better to assemble it closer to the tank to possibly dampen fuel pressure fluctuations?
3. Do you think I'd need a pressure accumulator in the system? Looks like hardly anyone uses it over here.

Best regards,
Jan

[R100RT]

The returnless system has been used on production vehicles for many years. For example, our stock 2000 Jeep Grand Cherokee has pump in tank, pressure filter/ regulator just beyond the tank, and returnless pressure line all the way to the front and fuel rail. No issues with airation or heat but they are sensitive to a maintenance of pressure in the end circuit when parked till next operation. A classic no start situation can develop if the regulator doesn't remain bubble tight, or if the pump develops back leakage - as in a tired shaft seal.
Go for it (welcome to the forums)

[Jann]

Thank you for your answer! I'll be very careful connecting the fuel pipes to avoid potential leaks!

I'll be still grateful for any comments, especially from people using returnless rails in a similar manner.

BR,
Jan

[old guy]

I ran a Suzuki TL1000 on a race bike with the same setup. The regulator was about 12 inches frm the fuel rail and never had any problems. What kind of vehicle is this on?

[Jann]

Hi Old Guy,
it is a two-stroke 3-cylinder old east-german car, Wartburg. It's not really for racing purposes. I just want to learn EFI specifics and I'm curious how much this change can influence this antique.

[whittlebeast]

Your setup should work fine. I run the same configuration in my race car. I have everything except the fuel rail in the back of the car.

Andy