Fuel Rail Question

[BinoX]

I\'ve been having a fuelling issue with my RX7 since it\'s rebuild.

I\'ve checked everything that I can think of without stipping it back down to the injectors...

This reminded me, that when I was doing the rebuild there was an anomaly with the secondary fuel rail that I never did work out and I think I may have just put it how I thought just to get going...

Anyway, attached is a picture of the fuel rail (actually it\'s my spare fuel rail that I dug out for this pic), could someone that knows please make sure that I\'ve labelled it correctly. It\'s mainly the vac hose situation that I\'m confused about...

1 is obviously the fuel input (coming from the primary rail)
2 and 3 are obviously the injector holes
4 seems to be the fuel return hose
5 and 6 both appear to be vac nipples, but all the diagrams I could find only showed 1 vac nipple... so not really sure what to do with them, can\'t remember what I ended up doing in the engine bay either......

Thanks in advance and sorry for all the recent questioning

[Ricco_04]

Looks correct to me.

Is that from a uk car?

[Prof]

I\'d certainly say that the end most vac line is the one that will correctly regulate fuel pressure.
 
On these rails with 2, I am not sure what the 2nd nipple is for.

[BinoX]

Yes, it\'s a UK spec car... and I have 2 identical fuel rails.

I\'m not really sure what the lines are for either... I think they\'re both connected to vac (where the old tubes seemed to want to flex to) But I really don\'t see how having a vac tube on both sides is going to help anything... I would have though it would make it worse....

Maybe it\'s time for some aftermarket rails?

[Prof]

It\'s just possible that the UK car\'s had this extra nipple to work with the PRC valve - basically it cut\'s the vacuum to the fuel rail (raising the pressure at idle) when the engine is started warm, to prevent or reduce percolation of the fuel.
 
I have an S4 secondary rail on mine, it was modified to take aftermarket fuel components.  The FPR part was removed - so I have an outboard one.  I did check my old S5 one, and that had both nipples too.  The PDF I have for the car is for the US model, and it only shows one vacuum nipple.

[BinoX]

Do you think I could get away with only having the end most one attached? Because that\'ll probably be better for the car than having them both connected to standard vac fittings

I probably will get an aftermarket fuel rail and external FPR when I have a bit more money... I\'m also going to do a rats nest removal at some point, but I\'d like the car working properly 1st so that I know any problems haven\'t been caused by me fiddling.