I am trying to identify a cause for a slight engine surge when i have both Rotax fuel pumps on to switch fuel tanks and then subsequently turn off one of two pumps.
I have isolated it to only when feeding from the right tank, and only when turning off the number 1 pump. I have not had it replicate at idle or full power and only had it intermittently replicate from about 30-70% power.
I also have a fuel boost pump running in the wing roots.
It feels like im going down the highway and then someone hit the brakes for just a split second and then all is normal.
With have a video and it shows fuel pressure at 43.8 with both pumps on. A split second after I turn off the number one pump the fuel pressure dropped to 41.3. Engine RPM went from 5190 to 5060. Again this is just for a split second and then it recovers.
Any thoughts on cause and a possible fix?
