Fuel Pressure fluctuations? problems?

Same problem as above; psi variance on Garmin G3X 4.5 to 6.2. Kitfox S7 with 912 ULS; return line installed. Engine RPMs are consistently stable and the measured psi is stable. I’ve read the SBs. Checked for fuel line leaks, loose connections and weak crimps - none. Re-crimped sensor connections - no joy. Considering replacing the Kavlico P4055-15G 0-15 psi sensor, but they’re no longer available. I checked the Garmin Installation Manual Table 21-1 for an alternate, again no joy as Garmin’s 0-15 psi sensor is also not available. 

What have I missed? Is there an alternative sensor one might suggest? The wife suggested Valium. 

I see only older threads on this and perhaps that means most people aren’t having problems. 
Anyway. My Rans S6 with gravity only fuel system has worked flawlessly with the Pierburg Switched to new corona Italy and before I return to service I’m required to test. I have a liquid filled gauge plumbed into the port carb supply. Have run engine 4 times for oil purge, compression test…

I had replaced all the fuel hoses and installed one of the Golan mini filters. I flow-tested it and an automotive filter at minimum fuel level in tanks. The flow rate was 16 and 20 gallons per hour respectively. I average about 4 flying. With the mini filter, the gauge ran 4 psi for a while before slowly dropping to about 3. The auto filter started at 5 psi stable for several minutes then after getting oil temp up to 200 it dropped slowly in a linear decline as the high rpm run went on, ending about 3 psi or possibly lower. 
So my question is, does this slow steady drop indicate reduced demand as the flow stabilizes with the carb requirement? Or should the pressure remain more in the midrange. What worries me is the trend seems to be to just get lower and lower pressure. Even though so far it is above 2.2 which means it’s in spec. 
Quit checking and go fly? Or is this a problem. 

Hi Julian,

Where in the fuel delivery system are these filters installed?

If you are using in line automotive style filters, I would advise they be installed in location where they can be inspected at short regular intervals (daily is best) one filter on each tank supply line. If you have a seperate boost/auxiliary pump line, have one on this as well.

Do not use sintered bronze or pleated paper filters. Do use gauze filters, that meet the Rotax recommended filtration standards.

I don't like filters that:

1. Can not be easily inspected for contaminant build up. 

2. Have a small area of filter medium that can block too readily.

3. if you must have a filter that can not be easily inspected, go for one that can be tested/drained before the first flight of the day.