Non-return fuel system on 202???

[stevemc32]

So I'm way out of my depth on this one and have been researching but just can't figure it out.

I'm delco-ing a VK 202 which is nothing new but I was planning on using a VZ Commodore in-tank fuel pump retrofitted into my existing (Torana) fuel tank. I was pretty happy with this mod until I found out the VZ uses a non-return fuel system running at 4 bar fuel pressure where the original VK system operates at 3 bar. I'm happy that I understand sufficiently how the VK system works at maintaining 3 bar over the manifold pressure using the diaphragm regulator but to be honest I have no idea how the VZ system would maintain a constant pressure with respect to the manifold.

Would it be possible to run the VK system as non-return at 4 bar using $12p and if so what modifications would be necessary to the system? If it is too difficult to achieve this the other option might be to remove the regulator from the VZ pump system and run a normal return but I haven't looked to see if this is viable.

Any help on this one would be much appreciated.

Cheers,
Steve.

[Jayme]

thats the thing... the VZ doesnt maintain a constant pressure with respect to the manifold. it just maintains a constant pressure with respect to the atmosphere and the tune is altered to compensate for the lower flow rate as the pressure increases inside the manifold. they are also able to do this as the new type injectors can handle a wider range pf pressures. in theory it shouldnt matter too much, but if it was me id be using a reg up at the mainfold and remove the one from the tank.

[stevemc32]

Thanks Jayme, so the tune sorts out the pressure differential, had me stumped how it worked...