Garmin G3X Installation Manual page 750

Fuel Flow Calibration – The Fuel Flow input requires calibration as detailed below.
K-Factor – Enter the 'K' factor for the fuel flow sensor (Section 21.3.11.1).
When installing the fuel flow sensor, the installer should take note of number on the tag attached to the
sensor (if applicable). This number is the calibrated K factor of the sensor. For sensors that are not
supplied with a specific calibration value, use the default K factor value provided.
The K-Factor represents the number of electrical pulses output by the sensor per gallon of fuel flow.
Aspects unique to each installation will affect the accuracy of the initial K-Factor, and as a result, the K-
Factor must generally be adjusted up or down to increase the accuracy of the fuel flow calibration.
If the fuel usage reported by the G3X differs from the actual fuel usage, as measured at the fuel pump (or
other trusted method of measurement), use the following formula to calculate a corrected K-Factor, which
can then be used to calibrate the fuel flow.
Corrected K-Factor = ( [G3X reported fuel used] x [previous K-factor] ) / [actual fuel used].
For differential fuel flow installations (when a return flow meter is used) the K-factor adjustment applies to
the normal (forward) flow sensor only. The K-factor must be adjusted until the displayed Net Fuel Flow
equals the Forward Flow minus the Return Flow (see preceding figure).
Full Fuel – Sets the Full Fuel quantity for the fuel computer. Set according to the fuel tank capacity (set to
zero if not used).
Partial Fuel 1 & 2 – The Partial Fuel values may be used if the fuel tanks have 'tabs' or some other method
of putting in a known quantity of fuel (other than completely full tanks). If the Partial Fuel function is not
applicable or not desired, these settings can be left blank or set to zero.
Fuel Used Reset - This setting is used to select what resets the fuel calculator "Fuel Used" value to zero. If
the Manual setting is used, the Fuel Used value is reset manually by the pilot via the Engine page (see
following figure). If the Auto setting is used, the Fuel Used value is reset automatically at the start of a
new flight (one time only per power cycle of the display). The fuel-used value can still be reset or changed
manually by the pilot via the Engine page (if the Auto setting is used).
Fill Threshold – This setting is used to determine if the fuel quantity should be confirmed upon system
power up. During power up, the system compares the current fuel quantity to the fuel quantity recorded
190-01115-01 G3X/G3X Touch Install Manual - GDU 45X/46X Config and Post Install Checkout
Rev. AA Page 32-155