Fuel Pressure readings and fluctuations

[kjmorris2023]

1) We have a Dynon install on an 1979 A-36TC with a TSIO-520 UB turbocharged. Before upgrade FP was 3.2 psi or so idle, about 15.8 psi Max power, and around 6psi LOP cruise. Now with Dynon EMS it's about 4.3 idle, 27.8 Max power and around 7.8 LOP. Other Guru's have mentioned that maybe the transmitter is located in the line prior to the fuel control rather than after the fuel control. Unmetered versus metered fuel pressure. Can you tell me where the Dynon transmitter would be located?

2) At full throttle were getting a fluctuation in the pressure. Plus or minus 4 psi. Steady as a rock at all other power settings. Dynon Tech can you shed any light?

Attaching engine data last flight

 

[Corefile]

what are you using for graphing engine monitoring data?

 

[kjmorris2023]

Using Savvy Aviation. Also fluctuations are also visible on HDX. ABS technical advisor asked these questions:
Is the fuel flow the same as it was on the other unit that was removed? Yes
The metered fuel pressure at takeoff 36" MP should be 14.4-16.0 PSI. It was approx 15.8 before when we had the AuRacle
In most installations fuel pressure is picked up from the manifold valve on the top of the engine.
There are two connections to the manifold valve.
On one side of the valve is the input from the fuel control.
On the other side is the fuel pressure pickup.
There may be a setup in the Dynon system for the transducer that was used, confirm that the correct data for transducer was entered. Maybe someone at Dynon can help me with these settings and I can check them.

 

[kjmorris2023]

My lead avionics mechanic wrote back and I quote
The fuel pressure sensor is not on the top of the engine, its at the back of the engine on the Fuel control unit, before the fuel flow sender. I can’t find a picture of that area from the installation- if you send me a picture of the back of the left section of the engine I should be able to point you to where it is. The settings I will guarantee are correct for that sender. Its just weird how its fine at other power settings. My thinking would be if the sensor was on the unmetered side then it would be wrong at all power settings. If it needs the sender moved to a different location up by the fuel spider we can easily do that when we do the autopilot

 

[kjmorris2023]

Any Dynon Subject Matter Experts here to talk about mounting options and is there a best practice.

 

[Dynon]

Your best bet here is to get in touch with our technical support department correctly to work this issue. Their contact information is in our signature.