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Fuel pressure drops in flight.

seagull

Well Known Member
Has anyone had or heard of a problem where the fuel pressure drops from 5.1 to to 3.8psi randomly?
I have seen this on my Dynon charts for the past few months. I am thinking it might be the sensor and will add a “T” and a steam gauge inline to verify.
 
Remove the single wire on the sender,, clean it check the crimp if applicable and reinstall. Check the ground wire if a two terminal sender. If that offers no change replace the sender unit.
 
I’ve seen this happen on two fuel injected RV-7’s.

Turns out both aircraft had small fuel leaks at the fuel pump. My thought is air was getting sucked into the line.

Tighten the fittings at the pump / inline filter and the problem went away.
 
I've seen this.

I experienced occasional intermittent fuel pressure drops, typically when descending from higher than usual altitudes (ie. pulling back on the throttle) and often when flying over or near water (probably coincidence, but sure gets your attention). Would fall into yellow range, and sometimes drop into the red for a few seconds. I blamed summer car gas fuel blends and even replaced the Kavlico pressure sensor at one point. Seemed to go away for a while but would still happen from time to time. Could not figure it out and admittedly became complacent.

But after replacing both the Rotax engine driven fuel pump and the Facet pump at the 5 year point my fuel pressure indication was noticeably higher in cruise. I haven't seen fluctuations occur now for several years. Very likely was a failing Rotax pump that I should have replaced years earlier. Lesson learned.
 
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