I need to backtrack on my statement from earlier in this post. After doing some research, it does seem that Rotax has a pressure issue in some instances where during climbout the pressure can drop to an indication that sets off an alarm.
I still find it hard to believe that Rotax has that many bad fuel pumps. But, if the pump isnt supplied with sufficient fuel to begin with, then yes it cant develop enough working pressure to stay in the 'safe' zone.
So a couple of questions for thought here:
1) how much fuel pressure can the carbs take before you overload the needle and seats and cause a dumping situation? Maybe Roger Lee can answer that one.
2) On another forum there was a post about using a different boost pump that apparently solved that builders issue. So---is the Facet pump that Vans is using the same pump as in other carbureted models of Vans planes? And is that pump still wired to run all the time?
3) On these planes that have this issue, has anyone plumbed in 2 mechanical gauges---one just after the boost pump, and one just upstream from the fuel pressure sender? That would check the system and all the tube routings, shutoff valve, flow trransducer, gascolator, etc, and give a good indication of the pressure drop between the 2 gauges.
4) Since it appears that this is a problem with the Rotax 912's, maybe we can figure out how to solve it.
Other ideas??
Tom