S52 Fuel Rail flow direction

[Genes1s]

I took things apart and made a rookie move not paying attention which is inlet/outlet. I know which hose is the supply/return. The question is which one is the inlet of the fuel rail, the round tube that is on top of the rectangular tubing that houses the injectors OR the other way around. Or does it matter since it is a loop that will get pressurized anyway.

Cylinder 1 is the very left, cylinder 6 by the 2 opening of the tubing, is this the flow direction?



Or the other way? or does it matter.

Thanks

[pbonsalb]

I remember figuring it out once. I think I studied the diagram in real oem. The regulator is in the return.

[Genes1s]

I remember figuring it out once. I think I studied the diagram in real oem. The regulator is in the return.

Real OEM dia isn't the same though. The Real OEM dia has one opening on each end instead of what I have 2 opening on one end.

http://www.realoem.com/bmw/enUS/show...diagId=13_1719

[Braymond141]

https://www.ebay.com/itm/BMW-E36-Fue...IAAOSwPh5ZLNIg

There you go. Mystery solved. The diagram you posted in post 1 is correct.

[Genes1s]

Thanks for the respond.

The more I think about this, I don't think it matters which opening should be the inlet or outlet, as long as you using the correct supply line, the rail/injectors is always behind the FPR behind which will get pressurized correctly. The FPR is always after in the return line, to my knowledge and that makes sense.

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[Braymond141]

No, it matters. Hook it up correctly.

[Genes1s]

No, it matters. Hook it up correctly.

Please explain why it matters to help me understand better on how the system works

[Hova]

Please explain why it matters to help me understand better on how the system works

If you reverse the lines there will be no fuel flow through the rail. There is a check valve in the system.

It matters.

[pbonsalb]

I don’t think there is a check valve after the regulator (or before it depending on the direction you are looking from). I think the question is whether the 2 lines from the obd2 regulator to and from the rail must be in a certain order. The regulator end matters but the rail end does not seem to. The car will actually run fine either way. I mixed them up years ago when running the stock obd2 regulator with no ill effects and I was flowing as much as 3x stock flow. But I studied how the regulator worked and real oem and pictures and figured out what the factory routing was and went back to it to be correct. Made no difference in running. Unfortunately I cannot recall and can’t go look at my car because I now use an aftermarket regulator. There is probably some theoretical difference, but I don’t know what it is.

[Genes1s]

I don’t think there is a check valve after the regulator. I think the question is whether the 2 lines from the obd2 regulator to and from the rail must be in a certain order. The regulator end matters but the rail end does not seem to. The car will actually run fine either way. I mixed them up years ago when running the stock obd2 regulator with no ill effects and I was flowing as much as 3x stock flow. But I studied how the regulator worked and real oem and pictures and figured out what the factory routing was and went back to it to be correct. Made no difference in running. Unfortunately I cannot recall and can’t go look at my car because I now use an aftermarket regulator. There is probably some theoretical difference, but I don’t know what it is.

This^. Maybe I didn't explain it well enough. I looked at a friend M Coupe with S52 and the inlet is going to the top round tubing and return thru the injectors and out, even said in the M Couple Bentley manual. So, I proceeded the installation like that just like I originally drew up.