Fuel pressure fluctuations

 there is a new 912iS service instruction (PAC) which addresses a fuel pressure variation problem which some aircraft seem to be bothered with. The instruction describes the measurement method to determine the max allowable variation and provides an additional regulator to be installed at the input rail fitting. Don't remember the SI number but it can be accessed at flyrotax.com.

I have the same problem: RV12iS, before engine start, fuel pressure with one elec pump 3 bar, with two elec pumps 3.1 bar. After engine start: fuel pressure with two pumps 2.8 bar, with one pump 2.7 bar and the „low fuel pressure“ warning comes on.
Engine running smooth.
Then, when increasing rpm above about 3000rpm, fuel pressure comes back to normal, 3 bar.
Whats wrong here? If i reduce the rpm again to 2200, pressure with 2 pumps again 2.8 bar.

Karl,

You may want to start a new Topic so people will see your question on the top page.

Good idea, thanks!