I have spent MONTHS and $$$$ diligently trouble shooting this!
Replacing parts, researching everything, contacting the US importer, communicating with other owners with similar problems, etc.
Here's where it's at:
1) Mechanical fuel pressure gauge testing correlated with the Dynon readings. The problem is not electronic, sender, or Dynon.
2) US Sport Aircraft has updated the fuel system in the new SportCruisers. The whole system is completely different. Fuel distribution, routing, fuel pressure system, etc.. The main feature is a CHECK VALVE related to the electric pump and main fuel feed line to the mechanical pump, and also the elimination of a redundant fuel line. An upgrade kit is available for previous years.
3) Research indicates that ADDITIONAL RESTRICTION OF THE FUEL RETURN LINE would raise fuel pressures. I have heard of EXPERIMENTAL RV-12's having success with this. (Different rules about modification apply of course.)
4) Many aircraft with low wing, the NEW PUMP, and FUEL RETURN LINE are experiencing low fuel pressure issues, especially when operating in hot climates. Specific models that I have heard of include: SportCruiser, RV-12, Sting, etc.
5) In my opinion, it is VERY LAME that at least one major manufacturer requires the electric pump to be on at all times. That should NOT be required or necessary!
6) This is an INTERMITTENT problem that SOME aircraft experience under SOME conditions, making it especially troublesome.
7) There are many older model aircraft operating with NO FUEL RETURN LINE at all, running very simple and reliable fuel systems... and I'm not hearing any complaints!
It is extremely FRUSTRATING that "improved" systems and "improved" parts subject owners to theses worrisome issues.
** Looking at all available information and options to resolve this issue and expect progress. **