Do I have an Integrated Orifice in My Fuel Block?

Speculation:

The fuel return line must have a flow restrictor in place to ensure that there is sufficient volume of fuel being delivered, at all times, to the carburettors. Too large a jet and the carburettors may be starved of fuel. Too small a jet may lead to ineffective clearing of fuel vapour. 

It seems to me that the (Green) Item 6 in the schematic is showing two diffrent the locations of the restrictor (usually a Mikuni #35 jet) depending on how you configure (Options 1 & 2) the Fuel Manifold.

Option 1 is for a fuel pressure line - Barb #2

Option 2 is without the fuel pressure line.

Are you intending to have a fuel pressure read out? If so you will have to go with Option 1 (Barb #2) with the restrictor jet in Barb #5😈

The picture show an engine fitted with the TSO fuel lines from Rotax.  Given it has a single output barb you have the restrictor already mounted in the banjo bolt that is marked with "FUEL" engraved on top.  The return line would have to be connected here.   There is an option to install a double barb outlet with the restrictor if going to a pressure gauge.  The end of the block has a bolt installed and this is normally used in the case of mounting your pressure sensor directly to the block.  

Cheers

Thank you, Sean.

I was pretty sure this was the case.  Thanks, Wizard for confirming!

If in doubt, just disassemble the banjo bolts and look at the pieces; it will be obvious where/if a restrictor jet is installed.