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Issac:
Im certainly not the expert on the TSIO 550 but I have to wonder why
you would want to repair something that doesnt appear to be broken???
I note that your idle fuel pressure average is close to the bottom of
the acceptable range (7-9psi) until you passed the 400 hr point and
then it dropped dramatically.
Did you have any engine work done about then? In my experience,
changing any one of the engine parameters will affect all the others,
somewhat.
TCM provides detailed instructions on how to adjust idle fuel
pressure. ( I can send you the spec # if you need it)
BTW, TCM only gives specs for WOT fuel pressure, fuel flows, MP and
RPM. Do you have any info on these parameters?
Also, what is your RPM rise when you pull the mixture to shut down the engine???
Happy to discuss problem further
Regards, Bill Hogarty
On Mon, Jul 30, 2012 at 10:52 AM, Isaac Heizer <ijheizer@comcast.net> wrote:
> My ES-P with a TSIO 550E, 660 hrs since new, no longer reliably idles unless
> the electric fuel pump is running on low. This is new behavior in the past
> 10 hours or so. The engine is stock except for GAMIs and was originally set
> up to SID 97-3E but the fuel system hasn't been touched since then. It's
> apparent from the G900X's fuel pressure display that the idle fuel pressure
> is too low, and we can most likely readjust the pressures back to spec. But
> my question is "is the low idle pressure simply normal wear and tear, or is
> something abnormal happening?"
>
> I plotted the minimum idle fuel pressure for the last 450 engine operating
> hours (MinimumIdleFuelPressure.jpg). Each marker is the minimum fuel
> pressure during a single flight while the engine was idling at start of the
> flight. I defined idle as engine running for at least 45 seconds, RPM
> between 700 and 1000 RPM, and oil temperature 120 degrees or cooler. It's
> clear to me the minimum idle pressure has been slowly declining for the
> entire time, but it started a steeper drop about 100 hours ago.
>
> I plotted the minimum fuel pressure during climb, when the boost pump was
> likely off (MinimumClimbFuelPressure.jpg). Each marker is the minimum fuel
> pressure during a single flight. I considered data points where the RPM was
> between 2450 and 2550, MAP between 29 and 32, and altitude below 9000' -- I
> think these are likely times when I had not activated the boost pump. I
> don't see anything weird about this plot, other than the minimum pressure
> has been rising (?)
>
> Neither my mechanic nor I really know the wear pattern for the mechanical
> fuel pump and related assemblies. I really want to conclude that we can
> simply adjust the fuel pressure back to spec and keep flying. But there is
> so much expertise on this forum, I'm wondering if anybody has better advice.
>
> Thanks
> isaac heizer
> N7842K
>
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