Frank,
I too have had some inconsistencies but mine seems to be a result of
differences in fuel. With Mogas (auto 94 octane fuel), My Westach gauge
with Princeton 5-S sender was perfect, but when I began using 100LL my
fuel gauge has been inconsitent on the low side. I have to recalibrate
everytime I switch gas, and with only half a tank it is awful. Luckily
the sight gauge works as does the JPI fuel totalizer.
Your system of a tube located behind the baggage compartment is a bit
different, and I would check that the tube does not have a bubble in it.
In flight, the bubble may become dislodged. Since it is behind the
baggage bay, it may not be visible to validate there is no bubble. Also
if you have the sensor tube detached from the sender circuit, then the
small vent hole in the outer aluminum tube may be leaning against the
fuel tube preventing full venting of the capacitance tube. That said,
if all is well behind the bulkhead:
Provided you have not been switching fuels, and since the problem is
with only the upper end, it does sound like a bad sender. The
Princeton, Skysport and Westach probes are not serviceable. They are
remove and replace items I am afraid.
Regards,
Bud Yerly
Custom Flight Creations, Inc.
www.customflightcreations.com<http://www.customflightcreations.com/>
(813) 653-4989
----- Original Message -----
From: Frank Mycroft<mailto:frankm@clara.net>
To: europa-list@matronics.com<mailto:europa-list@matronics.com>
Sent: Sunday, May 15, 2011 2:06 PM
Subject: Europa-List: Faulty fuel gauge
I have a capacitance fuel gauge sender in a tube behind the baggage
compartment, and a VDO gauge on the panel. For some reason the gauge
refuses to read more than about 5/8ths full even when the tank is
brimming. I had this fault intermittently last summer, but after about
an hour's flying the fault corrected itself and the reading returned to
normal. Once the tank really is below 5/8ths full the gauge starts
functioning normally right down to empty. The vent appears to be clear
and blowing down it makes no difference. It was recently completely
emptied when I was replacing a fuel pipe, so there is no foreign
substance in the tube. The wiring appears to be sound. It's as though
the top part of the probe is inneffective, but as I don't understand
these things I would welcome advice. should I pull the capacitance tube
apart to look at it?
Frank Mycroft
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avigator?Europa-List>
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