First Engine Run Low Fuel Pressure

Bill do you recommend this fuel bypass nozzle? 

http://www.andair.co.uk/product/rotax-912is-nozzle/?bi=0

Also isn't it possible that my fuel pressure sender is simply mis-calibrated? What pressure should a 912 see when engine is not running, with one fuel pump engaged and start power switch on (I.e power to pumps but not starting the engine). In this configuration Im seeing 43-44 psi. Of course without a bypass jet (YET!)

Thanks! 

Any thoughts Bill? Both the pumps are consistent when the engine is running. Could it be as simple as miscalibration? What psi do people typically see before start? 

When folks have problems with oil pressure indications, the first step is always to insert a mechanical gauge and cross check it against the suspect reading. Maybe that would be a good idea in this case as well.

I think I may have figured it out and let me know if this makes sense. The fuel pressure regulator is holding pressure relative to the manifold. My pressure gauge is just relative to outside air. So, I have correct pressure when the engine is not running and the manifold pressure = outside air pressure. When I start the engine the manifold pressure < outside air pressure. hence the fuel regulator drops the fuel pressure to compensate and my gauge shows low. Does the make sense? Theres an option in the G3X to change to 'relative to manifold pressure' and calibrate. The manual say this is needed for 912is and I just must have missed it. What do you guys think? 

Also can someone verify this is the correct nozzle to install for the fuel vapor bypass http://www.andair.co.uk/product/rotax-912is-nozzle/?bi=0

Thanks! 

I'm not an expert, but your hypothesis seems really reasonable Joe. On the the 914, you must measure differential fuel pressure relative to airbox pressure for almost the opposite reason (MAP > ambient P). If the manual says it's needed, and it's just a software tweek to display differential pressure, I imagine by the time you read this, you'll have found that all is well.