Fuel problems are just what I am currently looking at as the possible cause
of my intermittent rough running engine. Has anyone taken the time to check
the calibration of there sender unit to see how accurate it is? And if so
what fuel pressure you are seeing at different manifold pressures?
I don't trust the accuracy of my gauge and am I the process of running a
calibration table to see how it responds over the range of 3 - 15 psi. I
hooked up an analog pressure gauge I picked up from AutoZone over the
weekend and it gave me a moment of pause. The base reading at idle was about
4.2PSI as I went up to about 31 inches the gauge was seen to slowly climb to
about 6 and then was jumping rapidly between 6 and about 10psi. Not sure
what if anything the gauge has for damping but it did not look like any. My
UMA gauge never shows a pressure fluctuation of more then maybe .1.
I am taking a small air regulator and making a calibration stand to check
the analog gauge against the sender unit and a calibrated pressure gauge I
have. This should allow me to know voltages and pressure readings and set up
the EIS to read correctly over our pressure range.
I want to know what people see from the 914 at say 15, 20. 25, 30 MP. Not
differential but actual pressure.
Problem remains intermittent rough running engine starting about 25MP. When
is runs rough both carb vacuum readings are in sync, Changing left or right
mags has no effect, Left or right tank has no effect, One, both or other
fuel pump has no effect. Going to manual on the prop has no effect as does
switching the disable on the TCU. Start and re try and still runs rough. Put
the plane away and come back two days latter and it works great. Let it sit
a day and it might work or it might not... Oshkosh is calling and I am
afraid I'll be hanging out in my hanger at this rate :-(
Rich Schultz
N262AE
180 Hours
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